university 

Of 


OPTOMETRY  LIB. 


H.  A.  STOCKWELL 

OPTOMETRIST 

BERKELEY,  CALIF. 


Qj 


Clinics  in  Optometry 


A  compilation  of  Eye  Clinics  covering  fully  all  Errors  of  Refraction 

and  Anomalies  of  Muscles,  with  Methods  of  Examination, 

Tests  and  Corrections,  as  used  in  actual  practice 


A  Text-Book  of  the  Practice  of  Optometry 


By  C.  H.  Brown,  M.D. 

Graduate  University  of  Pennsylvania  ;  Professor  of  Principles  and  Practice  of  Optometry;  Formerly 
Physician  to  the  Philadelphia  Hospital ;  Author  of  The  Optician's  Manual,  Vols.  land  IT. 


WITH   ILLUSTRATIONS 


PUBLISHED   BY 

THE  KEYSTONE  PUBLISHING  CO. 

809-811-813  North  19th  Street,  Philadelphia,  U.S.A. 

1907 

All  rights  reserved 


[B. 


Copyright,  1907,  by 
The  Keystone  Publishing  Co. 


!ETRY 


PREFACE 


This  book  has  been  written  not  so  much  for  the  optical  student 
as  for  the  practitioner  of  optometry,  and  it  is  therefore  really  a 
manual  of  practice.  No  attempt  has  been  made  to  commence 
with  elementary  matters  and  systematically  pass  on  to  more 
advanced  subjects,  but  the  cases  have  been  taken  as  they  came 
and  as  they  are  likely  to  be  met  with  in  every-day  practice.  At 
the  same  time  the  explanation  of  the  principles  involved  in  each 
case  has  been  made  as  simple  as  possible,  and  the  method  of 
management  made  clear,  so  that  even  a  beginner  in  the  work 
will  have  no  difficulty  in  understanding  both  the  theory  and  the 
practice  in  each  case. 

As  these  clinics  cover  the  whole  range  of  optometrical  prac- 
tice, the  value  of  this  book  as  a  work  of  reference  in  difficult 
cases  becomes  evident,  as  the  proper  method  of  management  can 
be  found  in  a  moment.  It  is  hoped  the  spirit  of  this  book  may 
inspire  the  reader  to  more  painstaking  and  accurate  work,  and 
kindle  in  him  an  ambition  for  the  advancement  of  optometry. 


E75UVSI 


CONTENTS 


CLINIC  NO.  1  Page 

A  Case  of  Simple  Hypermetropic  Astigmatism 9 

CLINIC  NO.  2 

A  Case  of  Mixed  Heterophoria H 

clinic  no.  3 
Hypermetropic  Astigmatism  Simulating  Myopic 20 

clinic  no.  4 
A  Case  in  Practice  with  Hysterical  Complication— Is  Hysteria 

the  Cause  or  the  Result? 25 

clinic  no.  5 
A  Typical  Case  of  Hypermetropia 3° 

clinic  no.  6 
A  Case  of  Toxic  Amblyopia  from  Alcohol  and  Tobacco   ...      35 

clinic  no.  7 
A  Case  of  Refractive  Error  Diagnosed  as  Cataract     ....      41 

clinic  no.  8 
Compound  Hypermetropic  Astigmatism  and  Presbyopia  Showing 
when    Cylinders    May    and    Should    be    Omitted    from 
Reading  Glasses 46 

clinic  no.  9 
Presbyopia 52 

CLINIC  NO.  10 

Myopia 5§ 

clinic  no.  11 
Monocular  Vision 65 

clinic  no.  12 
Mixed  Astigmatism     . 7* 

clinic  no.  13 
Anisometropia 78 

CLINIC  NO.  14 

Convergent  Strabismus 85 

clinic  no.  15 
Divergent  Strabismus 91 

CLINIC  NO.  16 

Headache  in  Connection  with  Myopia  and  Exophoria   ....      97 


6  Clinics  in  Optojnetry 

CLINIC  NO.  17  Pag© 

Facultative  Hypermetropia     103 

clinic  no.  18 
Hyperphoria      109 

CLINIC  NO.  19 

A    Case    of    Astigmatism,  Illustrating    the    Value    of    the 

Ophthalmometer 115 

CLINIC  no.  20 
A  Case  of  Hypermetropia,  Illustrating  the  Fogging  Method    122 

clinic  no.  21 
Astigmatism  With  the  Rule 120 

CLINIC  no.  22 
Astigmatism  Against  the  Rule 134 

CLINIC  NO.  23 

Lenticular  Astigmatism      141 

CLINIC  NO.  24 

A  Case  of  High  Myopia     148 

clinic  no.  25 
Keratoconus  or  Conical  Cornea 155 

clinic  no.  26 
The  Value  of  Retinoscopy 163 

CLINIC  NO.  27 

A  Case  of   Pigmentary  -Retinitis,  Illustating  the  Value   of 

Ophthalmoscopy 17° 

CLINIC  NO.  28 

Albuminuric  Retinitis,  or  the  Retinitis  of  Bright's  Disease    177 

CLINIC  NO.  29 

Accommodative  Esophoria 184 

CLINIC  NO.  30 

Spasm  of  Accommodation 191 

CLINIC  N( ).  31 

Exophoria x99 

CLINIC  NO.  32 

Transposition  of  Lenses  as   Illustrated  by  a  Case  of   Mixed 

Astigmatism 207 

CLINIC  NO.  33 

Adjustment  of  Spectacles 215 

CLINIC  NO.  31 

Fitting  of  Eyeglasses     223 

clinic  no.  35 
Spectacles  and  Eyeglasses 231 

clinic  no.  36 
Inspection  OP  SPECTACLES  and  EYEGLASSES  AND  NEUTRALIZATION 

op  Lenses 240 


CLINICS  IN  OPTOMETRY 


A  Case  of  Simple  Hypermetropic  Astigmatism 

[Clinic  No.  i] 

J.  S.  E.,  a  young  man,  twenty-five  years  of  age,  was  sent  by 
his  family  physician.  The  symptoms  of  which  he  complains  are  as 
follows  :  Trouble  in  reading,  especially  at  night,  words  run  together, 
pains  in  head  and  drowsiness. 

The  question  was  asked  him,  as  should  be  done  in  every  case 
that  applies  for  relief,  whether  or  not  glasses  had  previously  been 
worn.  He  replied  that  he  was  given  glasses  some  four  years  ago 
by  an  optician,  but  they  were  not  comfortable,  and  he  never  could 
wear  them.  On  examination  by  the  lens  measure  they  proved  to  be 
O.  D.,  —  .25  D.  S.  C  —  .25  D.  cyl.  and  O.  S.,  —  .25  S. 

We  ask  the  patient  to  be  seated  and  direct  his  attention  to  the 
test  card  hanging  on  the  wall  directly  facing  him,  and  at  a  distance 
of  twenty  feet.  ' '  How  far  down  the  card  can  you  read  ?  "  is  the 
first  question,  and  in  reply  he  names  every  letter  on  the  No.  20  line. 
We  make  the  proper  note  in  our  record  book  that  vision  =  f#, 
which  means  that  with  both  eyes  open  while  seated  at  a  distance  of 
twenty  feet,  he  is  able  to  read  the  line  that  is  marked  20,  which 
indicates  that  the  acuteness  of  vision  is  up  to  the  normal  standard. 

Such  being  the  case  we  involuntarily  make  a  mental  criticism 
of  the  concave  glasses  which  had  been  prescribed  by  the  former  op- 
tician, and  we  can  readily  understand  why  they  never  were  comfort- 
able. We  want  to  treat  everyone  fairly  and  we  want  to  be  treated 
fairly  ourselves,  and  therefore  we  do  not  think  it  wise  to  condemn 
our  competitors.  One  can  scarcely  improve  his  own  reputation  by 
making  damaging  statements  about  the  work  of  others  engaged  in 
the  same  line  of  business  as  ourselves,  even  though  such  statements 
are  entirely  truthful.  It  is  far  better  to  make  no  comment,  to  say 
nothing. 

But  we  will  leave  our  patient  for  a  moment,  just  long  enough 
to  preach  a  little  sermon,  using  this  optician's  error  as  our  text. 
Let  us  take  a  few  moments  to  consider  this  matter. 

When  we  find  the  visual  acuteness  to  be  f$,  what  information 
is  to  be  gained  from  this  fact  ?  Presumably,  the  refraction  is  em- 
metropic, but  it  may  be  hypemetropic,  or  slightly  astigmatic,  that  is, 


IO  Clinics  in  Optometry 

hypermetropic  astigmatism.  //  cannot  be  myopic.  Normal  vision 
positively  precludes  myopia  or  myopic  astigmatism.  Therefore,  in 
a  case  like  this,  concave  lenses  must  not  be  tried  ;  they  must  not 
even  be  thought  of. 

How  did  the  other  optician  commit  such  a  grievous  error?  for 
the  prescribing  of  concave  lenses  in  the  presence  of  emmetropia  or 
hypermetropia  cannot  be  designated  in  any  other  way.  Perhaps  he 
took  the  weak  concave  lenses  from  his  trial  case  and  held  them 
before  his  patient's  eyes,  and  of  course  they  were  accepted.  Almost 
any  pair  of  eyes  can  see  through  weak  concave  lenses  at  a  distance. 
But  the  point  we  want  to  impress  is  that  concave  lenses  must  not  be 
tried  when  the  vision  is  normal,  and  if  every  optometrist  will  burn 
this  rule  into  his  brain,  it  will  act  as  a  danger  signal  to  prevent  him 
from  straying  into  paths  of  error,  and  also  as  a  guide  post  to  keep 
him  in  the  straight  and  narrow  path  of  optometric  rectitude. 

TESTING   WITH    TRIAL    LENSES 

We  turn  now  to  our  patient  and  commence  the  test  with  trial 
lenses.  We  place  the  opaque  disk  over  the  left  eye,  the  right  eye 
being  uncovered  and  ready  for  the  examination.  We  have  made 
the  statement  above  that  concave  lenses  should  not  be  tried  when 
the  visual  acuteness  is  normal.  Perhaps  we  had  better  make  a 
broader  rule  as  a  guide,  and  that  is  in  every  case  always  to  try  con- 
vex lenses  first.  In  accordance  therewith  we  place  a  +  .50  D. 
sphere  in  front  of  the  right  eye.  The  patient  does  not  reject  it  ab- 
solutely, neither  does  he  seem  inclined  to  accept  it  ;  he  is  in  doubt 
whether  there  is  an  improvement  or  not.  Then  we  take  this  sphere 
out  and  quickly  replace  it  with  a  +  .50  D.  cylinder,  with  its  axis  at 
900,  so  that  the  patient  can  mentally  contrast  the  effect  of  the  two 
lenses,  and  he  at  once  indicates  his  preference  for  the  latter  as  being 
the  best.  We  repeat  the  trial  of  these  two  lenses,  placing  first  one 
and  then  the  other  before  the  eye,  and  the  patient  unhesitatingly 
prefers  the  cylinder,  which  we  then  slowly  rotate  from  the  vertical 
meridian  first  to  the  right  and  then  to  the  left.  The  patient  is  all 
the  time  looking  at  the  No.  20  line  of  letters  on  the  test  card,  and 
he  says,  as  the  axis  is  rotated  from  the  90th  meridian,  that  the  let- 
ters become  less  distinct,  and  after  several  trials  we  conclude  that 
the  proper  place  for  the  axis  of  the  cylinder  is  at  900.  We  then  place 
alternately  in  front  of  this  lens  a  +  .25  cyl.  axis  900,  and  a  -j-  -25 
S.,  both  of  which  are  rejected.      In  order  to  verify  the  rejection  of 


A  Case  of  Simple  Hypermetropic  Astigmatism  1 1 

the  cylinder,  we  remove  the  +  .50  cyl.  and  place  in  its  stead 
a  _|-  . 75  cyl.,  with  its  axis  in  the  same  position,  when  the 
patient  says  the  former  is  the  better.  We  now  feel  pretty  sure 
that  the  +  .50  D.  cyl.  axis  900  is  the  proper  correcting  lens. 
This  represents  a  case  of  simple  hypermetropic  astigmatism  with 
the  rule. 

Perhaps  some  one  may  ask  why  we  did  not  try  the  card  of 
radiating  lines  in  order  to  detect  the  presence  of  astigmatism  in  this 
case.  We  reply  that  we  do  not  consider  this  a  reliable  test  in  a 
case  of  slight  hypermetropic  astigmatism,  because  the  ciliary  muscle 
is  so  quickly  brought  into  action,  and  by  the  irregular  contraction 
of  which  it  is  said  to  be  capable  the  defective  meridian  is  neutral- 
ized. Theoretically,  when  astigmatism  is  present,  on  account  of  the 
difference  in  refraction  of  the  two  chief  meridians,  the  lines  running 
in  one  direction  seem  blacker  and  more  distinct  than  those  in  the 
direction  at  right  angles,  and  therefore  when  a  variation  is  noticed 
in  the  distinctness  of  the  radiating  lines,  we  say  astigmatism  is  pre- 
sent. This  difference  depends  upon  the  fact  that  the  light  entering 
the  emmetropic  meridian  is  focused  upon  the  retina  and  is  distinct, 
while  the  rays  entering  the  ametropic  meridian  are  focused  in  front 
of  or  back  of  the  retina,  and  hence  are  indistinct.  But  if  the 
accommodation  is  brought  into  action  and  the  hypermetropic  meri- 
dian thus  made  emmetropic,  both  meridians  will  focus  upon  the 
retina,  and  consequently  no  difference  will  then  be  discernible 
between  the  radiating  lines. 

Another  reason  why  we  place  but  little  dependence  upon  this 
test  for  astigmatism,  is  that  in  the  lower  degrees  of  the  defect,  where 
the  differences  between  the  lines  can  be  but  slight,  the  patient  may 
be  unable  to  detect  them.  So  much  depends  upon  the  intelligence 
of  the  patient,  and  there  are  so  many  patients  whose  powers  of 
observation  are  but  little  developed,  that  the  value  of  this  test  in 
the  majority  of  cases  is  doubtful. 

Instead  of  the  card  of  radiating  lines  we  use  the  card  of  test 
letters,  and  practically  determine  the  existence  of  astigmatism  by  the 
acceptance  of  cylindrical  lenses.  If  the  patient  is  in  doubt  whether 
cylinders  are  better  than  spheres,  and  if  the  rotation  of  the  cylinder 
makes  vision  neither  better  or  worse,  astigmatism  is  probably 
absent.  But  if  the  cylinder  is  quickly  accepted,  and  if  its  rotation 
produces  a  decided  impairment  of  vision,  we  may  safely  conclude 
that  the  case  is  one  of  astigmatism. 


12  Clinics  in  Optometry 

We  now  try  the  left  eye.  The  +  .50  sphere  is  promptly 
rejected,  as  is  also  the  +  .50  cylinder,  with  its  axis  placed  at  900. 
Before  removing  the  latter,  however,  we  try  the  effect  of  rotation. 
As  the  axis  is  turned  to  the  right  vision  is  made  noticeably  worse, 
but  as  it  is  turned  to  the  left  an  improvement  is  perceptible,  although 
patient  says  that  vision  is  clearer  without  either  of  these  lenses. 
We  now  have  a  clue,  however  ;  the  fact  that  vision  is  improved  by 
rotation  of  the  cylinder  in  one  direction,  and  impaired  by  turning 
the  other  way,  indicates  astigmatism.  We  now  try  a  -f  .25  cylin- 
der, and  as  we  expected  it  is  at  once  accepted,  and  after  a  few  trials 
we  find  that  the  proper  position  for  the  axis  is  at  700. 

We  then  try  the  range  of  accommodation  and  find  the  patient 
can  read  the  smallest  print  from  4^  to  30  inches.  By  calling  to 
mind  what  the  normal  near  point  should  be  at  this  age,  we  know 
that  ArYz  inches  is  about  right  for  this  age,  and  that  therefore  the 
amplitude  of  accommodation  is  not  impaired. 

MUSCLE    TEST    BY    MADDOX  ROD 

We  pass  on  then  to  an  examination  of  the  muscular  equili- 
brium, and  for  this  purpose  we  prefer  the  Maddox  rod,  which  is 
placed  over  the  left  eye  in  a  horizontal  position.  We  say  to  the 
patient  that  he  will  see  a  reddish  vertical  streak  as  he  looks  at  the 
light  across  the  room,  and  we  ask  him  on  which  side  of  the  light 
the  streak  appears  to  be.  He  replies  that  it  is  on  the  left  side 
and  about  two  inches  away  from  it.  We  mentally  analyze  this  con- 
dition :  the  streak  on  the  same  side  as  the  eye,  over  which  the  rod 
is  placed,  means  a  homonymous  diplopia,  is  due  to  esophoria,  and 
is  correctible  by  a  prism  base  out.  We  therefore  place  a  prism  of 
i°,  with  base  out,  over  the  right  eye,  and  now  the  patient  says  that 
the  streak  runs  up  and  down  through  the  light,  and  we  make  a  note 
in  our  record  book  that  there  is  an  esophoria  of  i°.  This  is  a  not 
uncommon  condition  to  find,  and  it  is  too  slight  to  call  for  correction. 

We  then  turn  the  rod  around  to  the  vertical  position,  which 
causes  the  streak  to  be  seen  horizontally,  and  we  ask  the  patient 
what  position  it  assumes  with  reference  to  the  light,  and  he  replies 
that  it  passes  directly  through  it.  This  indicates  that  the  superior 
and  inferior  muscles  are  equally  balanced  and  that  there  is  no 
hyperphoria. 

Inasmuch  as  the  eyes  are  apt  to  vary  slightly  from  day  to  day, 
it  is  well  in  almost  any  error  of  refraction,  but  especially  in  astig- 


A  Case  of  Simple  Hypermetropic  Astigmatism  13 

matism,  to  repeat  the  examination.  We  therefore  ask  our  patient 
to  return  to-morrow,  explaining  to  him  the  care  that  should  be 
taken  in  prescribing  glasses.  When  he  returns  we  make  another 
examination  along  the  same  lines  as  before,  and  obtain  the  same 
result.  We  therefore  feel  that  we  are  justified  in  prescribing  the 
lenses  we  found  as  follows  : 

O.  D.,  +  .50  D.  cyl.  axis  900. 
O.  S.,  +  .25  D.  cyl.  axis  700. 

Which  we  advise  to  be  worn  constantly. 

If  the  second  examination  had  shown  a  different  result  from  the 
first,  we  should  have  asked  our  patient  to  return  a  third  time. 


A  Case  of  Mixed  Heterophoria 


[Clinic  No.  2] 

Mr.  R.  P.,  29  years  of  age,  bank  clerk.  The  symptoms  of 
which  this  gentleman  complains  are  indistinctness  of  vision,  especi- 
ally at  night,  with  occasional  pain  in  eyes  and  head. 

In  answer  to  our  inquiry  as  to  whether  he  has  ever  worn 
glasses,  patient  replies  that  he  was  fitted  with  glasses  about  eight 
years  ago,  but  he  has  never  worn  them  much  because  they  were  of 
no  benefit  to  him.  We  ask  to  see  them,  and  on  neutralization  we 
find  them  to  be  +  -5°  D.  spherical. 

We  now  proceed  to  determine  the  acuteness  of  vision,  and  we 
find  that  each  eye  separately  can  read  all  the  letters  on  the  No.  20 


find  that  he  can  read  the  smallest  type  as  close  as  4  inches  and  as 
far  away  as  20  inches.  This  near  point  of  4  inches  shows  an  ampli- 
tude of  accommodation  of  10  D.  We  recall  that  this  corresponds 
to  the  conditions  usually  found  at  20  years,  while  at  30  the  near 
point  normally  recedes  to  5^  inches,  which  represents  an  ampli- 
tude of  accommodation  of  7  D.  This  indicates  a  vigorous  condition 
of  the  accommodation  in  this  case  when  the  eyes  are  used  for  close 
vision. 

INFERENCE  FROM  THE  SYMPTOMS 

The  symptoms  complained  of  lead  us  to  suspect  hypermetropia 
or  hypermetropic  astigmatism.  In  order  to  get  an  idea  of  the  condi- 
tion of  the  refraction  we  make  a  hasty  trial  with  convex  lenses  held 
before  the  two  eyes  at  one  time,  and  we  find  that  a  pair  of  -j-  .  50 
are  accepted.  This  indicates  a  hypermetropic  condition  of  the 
refraction,  and  proves  that  there  is  no  tonic  spasm  of  accommodation 
in  spite  of  the  fact  that  the  ciliary  muscle  is  of  excessive  strength, 
as  shown  by  an  amplitude  of  10  D.  at  29  years  of  age. 

We  will  now  test  each  eye  separately,  and  we  find  that  the 
vision  of  the  right  eye  is  even  better  than  f$,  and  that  some  of  the 
letters  on  the  No.  1 5  line  are  legible.  We  try  a  -j-  .  50  D.  sphere 
and  it  is  promptly  rejected.  We  then  try  a  +  .25  D.  sphere  which 
is  accepted.     We  remove  this  sphere  and  replace  it  with  a  -f  .25 


A  Case  of  Mixed  Heterophoria  1 5 

D.  cyl.,  which  we  find  is  also  accepted  when  the  axis  is  placed 
at  1800.  In  comparing  these  two  lenses  and  quickly  changing 
from  one  to  the  other,  patient  is  unable  to  choose  between 
them.  We  therefore  make  a  note  in  our  record  book  that  the 
refraction  of  right  eye  is  represented  by  -f-  .  25  D.  S.  or  +  .  25  D. 
cyl.  axis  180°. 

On  examining  the  left  eye  we  find  the  vision  is  not  quite  \% 
full.  A  -f-  .50  D.  sphere  is  rejected,  but  a  +  .50  D.  cyl.  axis  900 
is  accepted.  We  rotate  the  cylinder  towards  the  left  and  patient 
says  letters  on  the  test  card  are  made  worse.  As  we  rotate  back 
towards  900  they  begin  to  improve,  and  keep  on  until  patient  again 
says  the  letters  begin  to  blur,  which  does  not  occur  until  the  axis 
has  passed  200  or  25 °  to  the  right  from  the  vertical.  After  a  few 
trials  we  find  that  no°  is  the  best  position  for  the  axis  of  the  lens. 

We  next  make  an  examination  with  the  ophthalmometer.  The 
right  eye  shows  an  overlapping  of  half  a  step  in  the  vertical  meri- 
dian. Now,  it  will  be  remembered  that  in  the  normal  cornea  there 
is  an  excess  of  curvature  and  of  refraction  in  the  verical  meridian  of 
about  this  amount,  and  therefore  in  astigmatism  with  the  rule  the 
same  allowance  must  be  made  ;  consequently  this  eye,  as  far  as  the 
curvatures  of  the  cornea  indicate,  is  devoid  of  astigmatism. 

The  left  eye  shows  an  overlapping  of  one  and  a  quarter  steps 
(1.25  D. )  in  the  vertical  meridian  :  after  making  the  usual  deduc- 
tion of  .50  D.  or  .75  D.  the  ophthalmometer  indicates  an  astigma- 
tism of  at  least  .  50  D.  with  the  rule. 

We  feel  safe  now  in  deciding  that  there  is  practically  no  astig- 
matism in  the  right  eye,  and  that  its  probable  refraction  is  repre- 
sented by  a  +  .25  D.  sphere. 

The  left  eye  is  undoubtedly  astigmatic  to  the  extent  of  +  .50 
D. ,  the  excess  of  curvature  being  at  or  near  the  vertical  meridian. 
The  ophthalmometer  shows  the  axis  of  the  cylinder  at  900,  while 
the  test  with  the  cylinders  calls  for  the  axis  at  no°.  We  would 
feel  better  satisfied  if  both  tests  agreed  as  to  the  location  of  the  axis  ; 
but  this  is  a  discrepancy  that  often  occurs,  and  in  such  a  case  we 
must  be  guided  by  the  answers  of  the  patient  who,  if  of  average  in- 
telligence, after  a  few  trials  will  be  able  to  decide  in  which  position 
the  cylinder  affords  the  best  vision.  We  therefore  repeat  the  test 
with  the  cylinder  by  rotating  it  from  one  position  to  another,  when 
we  find  that  Mr.  P.  adheres  to  his  statement  that  the  axis  at  uo° 
affords  the  best  vision. 


1 6  Clinics  in  Optometry 

What  is  the  result  of  our  examination  of  the  refraction  ?  O. 
D.,  +  .25  D.  S.  ;  O.  S.,  +  .50  D.  cyl.  axis  no° 

USE    OF    MADDOX    MULTIPLE    ROD 

The  next  step  in  the  examination  is  the  use  of  the  Maddox 
multiple  rod  to  determine  the  condition  of  the  muscular  equilibrium. 
We  place  it  in  a  horizontal  position  over  the  left  eye  and  ask  the 
patient  if  he  sees  a  red  streak  of  light  running  vertically,  and  if  so 
what  position  does  it  assume  with  regard  to  the  light  seen  by  the 
uncovered  eye.  He  replies  that  he  sees  it  and  that  it  is  about  one 
inch  to  the  left  of  the  light.  This  indicates  esophoria  of  low  degree. 
We  try  a  prism  of  i°,  with  base  out,  and  find  this  brings  the  red 
streak  of  light  directly  through  the  flame. 

We  turn  the  Maddox  rod  around  to  the  vertical  position, 
when  the  patient  sees  the  red  streak  running  horizontally,  and 
we  ask  him  what  position  it  assumes  with  regard  to  the  light, 
whether  above  or  below  or  through  it,  and  he  replies  that  the  red 
streak  runs  directly  through  the  center  of  the  light.  This  indicates 
a  proper  balance  of  the  vertical  muscles,  and  we  conclude  there 
is  no  hyperphoria.  The  dot  and  line  test  shows  2°  of  exophoria 
in  accommodation. 

This  concludes  the  examination  for  the  day,  and  in  accordance 
with  our  usual  custom  we  ask  the  patient  to  return  for  a  further  ex- 
amination, telling  him  we  think  it  advisable  to  make  at  least  three 
examinations  before  prescribing  glasses. 

On  the  second  visit  we  get  exactly  the  same  result  as  on  the 
first  day. 

But  on  the  third  day  we  uncover  a  condition  of  latent  hetero- 
phoria.  We  measure  the  power  of  convergence  and  of  divergence 
as  a  part  of  our  routine  method,  and  find  the  former  is  equal  to  2S0, 
which  is  normal,  while  the  latter  is  equal  only  to  30,  which  is  con- 
siderably below  normal. 

For  the  benefit  of  our  less  experienced  readers  we  will  say  that 
the  power  of  convergence  is  measured  by  the  strongest  pair  of 
prism,  bases  OUT,  which  the  eyes  are  able  to  overcome  and  main- 
tain the  light  single  at  a  distance  of  20  feet.  The  normal  power  is 
from  200  to  300,  but  which  can  be  trained  up  to  6o°. 

The  power  of  divergence  is  measured  by  the  strongest  prisms, 
bases  IN,  which  the  eyes  are  able  to  overcome  and  maintain  the 
light  single.      The  normal  standard  is  from  6°  to  8°. 


A  Case  of  Mixed  Heterophoria  17 

These  tests  show  in  this  case  a  weakness  of  the  divergent  mus- 
cles, the  eyes  being  given  over  to  the  stronger  convergent  muscles, 
which  causes  a  condition  of  esophoria. 

After  these  duction  tests,  when  each  muscle  is  called  upon  to 
exert  itself  to  the  utmost,  any  existing  spasm  of  a  single  muscle  is 
likely  to  be  broken  up,  and  the  true  condition  of  the  several  muscles 
can  the  better  be  determined.  We  now  try  the  Maddox  rod  on 
this  case,  and  instead  of  the  1  °  of  esophoria  which  we  found  on  the 
first  two  examinations,  there  is  now  an  esophoria  of  io°,  and  aright 
hyperphoria  of  1  °  has  become  manifest. 

Instead  of  prescribing  glasses  on  the  third  examination,  as  we 
expected,  we  tell  our  patient  that  there  have  been  some  new  devel- 
opments in  the  case  which  make  it  more  complicated,  aud  that  sev- 
eral more  examinations  will  be  required  in  order  to  clear  it  up. 

These  tests  resulted  as  follows  : 

Oct.  31,  1903.      Esophoria  io°.      Right  hyperphoria  i°. 
Nov.  2,      "  "  40.  "  "         i°. 

The  first  test  showed  an  exophoria  of  2°  at  the  reading  point, 
but  the  later  tests  of  the  muscular  balance  at  the  near  point  showed 
the  following  results : 

Oct.  31,  1903.      Esophoria  200. 

Nov.  2,       "  "  50. 

..        3>         „  ..  15o 

It  is  a  well-known  fact  that  the  muscular  balance  or  imbalance 
is  a  variable  quantity,  and  no  two  days  show  exactly  the  same  re- 
sults. It  is  also  a  fact  that  there  may  be  a  spasm  of  one  of  the 
extra-ocular  muscles,  which  masks  the  true  condition,  as  in  this 
case  the  test  of  the  muscles  at  the  reading  point  at  first  showed  an 
exophoria,  when  really  the  condition  is  one  of  esophoria. 

PROCEDURE    IN    CORRECTION 

The  later  developments  in  this  case  lead  us  to  suspect  that  the 
symptoms  are  perhaps  as  much  due  to  the  heterophoria  as  to  the 
error  of  refraction.  Ordinarily  we  think  it  proper  to  correct  the  re- 
fractive error  first.  Oftentimes  such  glasses  will  afford  perfect  relief 
to  all  the  symptoms,  and  by  relieving  the  strain  on  the  accommoda- 
tion the  heterophoria  gradually  passes  over  into  a  condition  of 
orthophoria.     If,   however,   the  symptoms   continue  unabated  in 


1 8  Clinics  in  Optometry 

spite  of  the  spheres  or  cylinders  that  have  been  worn,  then  we  ad- 
vise the  combination  of  prisms  for  the  correction  of  any  existing 
muscular  insufficiency. 

But  in  this  case  there  is  such  positive  evidence  of  spasm  of  the 
external  recti,  and  such  a  high  degree  of  esophoria  after  this  spasm 
had  been  removed,  that  we  think  it  best  to  give  him  a  prismatic  cor- 
rection at  once. 

The  amount  of  esophoria  varied  considerably  from  day  to  day, 
and  therefore  we  hardly  feel  justified  in  prescribing  a  prism  stronger 
than  30  for  its  correction.  The  hyperphoria  was  constant  after  it 
first  made  its  appearance  ;  on  three  days  it  was  i°,  and  on  one  oc- 
casion it  reached  2°.  We  will  therefore  prescribe  a  i°  prism  for 
the  correction  of  the  vertical  deviation. 

The  right  eye  is  patient's  best  eye,  and  as  the  amount  of 
hypermetropia  is  so  slight  we  will  not  correct  it.  We  will  place  the 
i°  over  this  eye,  a  plane  prism  without  any  spherical  or  cylindrical 
curvature. 

The  astigmatism  in  the  left  eye  cannot  be  ignored,  and  there- 
fore we  will  prescribe  the  indicated  cylinder  combined  with  the 
3°  prism. 

Our  prescription  reads  : 

O.  D.,  Prism  i°,  base  down. 

O.  S.,  +  .50  D.  cyl.  axis  no0  O  prism  30,  base  out. 

Perhaps  some  one  may  wonder  why  we  place  the  weaker  prism 
over  the  right  eye.  We  have  a  very  good  reason  for  this  ;  we 
want  to  interfere  as  little  as  possible  with  the  good  eye,  and  this  we 
do  by  placing  the  i°  prism  over  it.  The  30  prism  causes  a  more 
marked  displacement  of  objects,  which  would  be  much  more  notice- 
able, and  hence  more  annoying,  if  placed  over  the  good  eye  than  if 
placed  in  front  of  the  other  eye.  If  a  single  prism  is  prescribed  it 
should  always  be  placed  over  the  eye  with  the  least  acuteness  of 
vision.  If  the  optometrist  will  keep  this  in  mind  he  may  save  him- 
self annoyance  and  his  patient  discomfort,  and  he  may  be  able  to 
get  more  satisfaction  out  of  the  use  of  prisms. 

These  glasses  were  prescribed,  and  they  seem  to  have  filled  the 
bill  completely.  It  is  now  six  months  and  more  since  Mr.  P.  com- 
menced to  wear  them,  during  which  time  we  have  seen  him  on  sev- 
eral occasions  on  account  of  breaking  of  the  left  lens,  and  he  always 


A  Case  of  Mixed  Heterophoria  19 

speaks  in  the  highest  terms  of  the  comfort  and  relief  afforded  by  the 
glasses. 

Perhaps  it  might  be  well  to  say  that  prismatic  lenses  should  not 
be  set  in  frameless  mountings  on  account  of  the  liability  to  breakage 
at  the  apex  end  of  the  prism,  which  is  very  thin.  We  advised  this 
patient  to  have  frames,  but  he  preferred  frameless  mountings  with 
the  result  of  two  broken  lenses  since  he  has  been  wearing  them. 


Hypermetropic  Astigmatism  Simulating  Myopic 


[Clinic  No.  3] 

Mrs.  I.  A.,  aged  twenty-two,  complains  of  headache,  soreness 
over  eyes  and  twitching  of  lids. 

We  find  the  acuteness  of  vision  is  f $  in  each  eye. 

In  a  case  like  this  where  headache  is  the  chief  symptom,  and 
where  the  acuteness  of  vision  falls  somewhat  below  normal,  we  sus- 
pect astigmatism.  After  trial  of  lenses,  in  which  all  convexes  are 
rejected,  we  find  that  —  1  D.  cyl.  axis  1800,  is  accepted  for  each 
eye  separately,  and  raises  the  visual  acuity  to  f$.  We  therefore 
apparently  have  a  case  of  simple  myopic  astigmatism  ;  but  we  feel 
entirely  satisfied  with  the  result  of  our  first  examination,  not  enough 
so  to  justify  us  in  prescribing  glasses,  and  therefore  we  will  pursue 
our  investigation  further. 

We  give  her  the  small  reading  card  in  order  to  measure 
the  amplitude  of  accommodation,  and  find  that  she  can  read 
the  smallest  print  at  the  top  of  the  card  as  close  as  7  inches 
and  as  far  away  as  20  inches.  The  power  of  accommodation  is 
therefore  5.50  D.  We  recall  the  normal  near  point  at  this 
age  should  be  4^  inches,  representing  9  D.  of  accommoda- 
tion. We  are  impressed  at  once  with  the  fact  that  the  near 
point  has  receded  and  that  the  amplitude  of  accommodation  has 
lessened,  which  indicates  that  the  refraction  of  the  eyes  is  hyper- 
metropic, instead  of  myopic,  as  the  cylinders  chosen  would  lead 
us  to  believe. 

Let  us  stop  long  enough  to  remind  the  reader  that  in  hyper- 
metropia  there  is  a  deficiency  of  refractive  power,  which  must  be 
made  up  by  the  accommodation  ;  this  reduces  the  amount  of  avail- 
able accommodation  as  revealed  by  the  receded  near  point.  In 
manuals  of  refraction  will  be  found  several  tables  showing  the  posi- 
tion of  the  near  point  and  the  amount  of  accommodation  at  the 
different  ages.  It  is  well  for  the  optometrist  to  have  these  tables 
committed  to  memory,  so  that  knowing  the  age  of  his  patient  he 
can  quickly  and  mentally  note  if  there  is  any  departure  from  the 
normal  standard  and  whether  in  the  direction  of  deficiency  or  excess 
of  accommodation. 


Hypermetropic  Astigmatism  Simulating  Myopic  2 1 

Contrariwise  in  myopia  there  is  an  excess  of  refractive  power, 
thus  increasing  the  amplitude  of  accommodation,  which  surplus  is 
revealed  by  a  near  point  closer  than  the  normal  standard  for  that 
particular  age. 

Therefore  the  receded  near  point  in  this  case  and  the  dimin- 
ished amplitude  of  accommodation,  would  tend  to  show  that  the 
concave  cylinders  accepted  were  incorrect  and  would  rather  indicate 
a  hypermetropic  condition  of  refraction. 

DETERMINING    MUSCULAR    EQUILIBRIUM 

We  now  pass  on  to  determine  the  muscular  equilibrium, 
for  which  purpose  we  place  a  Maddox  rod  over  the  left  eye  in 
a  horizontal  position,  while  the  patient's  attention  is  directed 
to  the  light  on  the  other  side  of  the  room.  On  account  of  the 
dissimilarity  of  the  images  formed  on  the  two  retinae,  the  natural 
desire  for  binocular  fusion  is  interfered  with,  and  the  eyes  are 
given  over  to  the  action  of  the  muscles  uninfluenced  by  this 
instinct,  and  therefore  if  there  is  any  imbalance  it  at  once  becomes 
manifest. 

The  image  formed  in  the  right  eye  is  that  of  the  light  of  its 
natural  appearance,  while  the  image  formed  in  the  left  eye  is  a  ver- 
tical streak  of  light  of  a  reddish  tint. 

We  ask  patient  if  she  sees  a  red  streak  of  light,  and  she  replies 
that  she  does  not.  This  is  by  no  means  unusual,  and  the  young 
optometrist  need  not  be  worried  because  the  patient  fails  at  first  to 
see  the  streak  and  therefore  he  is  led  to  fear  that  he  may  not  be  able 
to  make  use  of  this  test,  which  is  really  the  most  reliable  at  our 
command  in  detecting  the  presence  of  heterophoria.  The  image  of 
the  natural  light  formed  in  the  right  eye  is  bright  and  clear  and 
engages  the  attention  of  the  brain  to  the  temporary  exclusion  of  the 
less  distinct  image  formed  in  the  eye  that  is  covered  by  the  Mad- 
dox rod,  because  the  latter  makes  a  much  less  marked  impression 
upon  the  visual  centers. 

We  cover  the  right  eye  for  a  second  and  then  the  streak  at 
once  becomes  visible,  and  on  removing  the  cover  the  streak  can 
usually  be  retained  in  the  visual  field  ;  or  perhaps  the  better  way  is 
to  rotate  the  Maddox  rod,  which  at  once  engages  the  attention  oi 
the  left  eye  and  makes  the  streak  noticeable.  And  whenever  the 
patient  loses  the  streak,  as  they  oftentimes  do,  one  or  two  rotations 
of  the  rod  at  once  brings  it  into  view. 


22  Clinics  in  Optometry 

We  make  use  of  this  little  trick  with  this  lady  and  we  ask  her 
again  if  she  sees  a  vertical  streak,  and  now  she  replies  in  the  affirma- 
tive. We  ask  her  on  which  side  of  the  light  the  streak  is  located, 
and  she  replies  ' '  to  the  left. ' '  Now,  let  us  consider  what  we  have 
found  :  the  rod  is  over  left  eye,  and  streak  is  seen  to  left  side  ;  this 
is  the  form  of  diplopia  that  is  termed  homonymous  ;  that  is,  right 
object  is  seen  by  right  eye  and  left  object  by  left  eye,  and  indicates 
a  condition  of  esophoria. 

USE    OF    PRISMS 

We  ask  the  patient  how  far  the  streak  appears  to  be  from  the 
light,  and  she  replies  "about  three  or  four  inches,"  which  amount 
of  displacement  indicates  at  least  several  degrees  of  defect.  We 
recall  that  in  esophoria  the  base  of  the  prism  must  be  placed  out, 
and  we  hold  a  prism  of  2°  in  this  position  before  the  eye  and  ask 
patient  what  effect  it  has  on  the  relative  positions  of  the  streak  and 
the  light.  She  replies  ' '  that  the  streak  is  still  on  the  left  of  the 
light,  but  closer  to  it,  perhaps  within  an  inch  or  two." 

We  then  try  a  30  prism  in  place  of  this  one,  and  patient  tells 
us  that  while  streak  is  still  on  the  left,  it  is  now  almost  in  contact 
with  the  light.  We  feel  as  if  this  is  about  the  measure  of  the 
esophoria,  but  before  entering  the  record  in  our  case  book,  we  will 
try  a  40  prism  base  out,  and  in  answer  to  our  inquiry  patient  says 
the  streak  is  now  at  least  one  inch  to  the  right.  This,  of  course,  is 
an  over-correction,  and  we  record  the  insufficiency  as  30. 

Now,  it  must  be  remembered  that  esophoria  is  usually  associ- 
ated with  a  hypermetropic  condition  of  refraction.  When  we  find 
hypermetroia  we  may  safely  expect  a  tendency  to  inward  deviation, 
and  when  the  muscle  tests  reveal  esophoria,  we  are  almost  sure  to 
find  that  the  refraction  of  the  eye  is  hypermetropic. 

Therefore  in  this  case,  in  spite  of  the  fact  that  concave  cylin- 
ders were  preferred,  the  diminished  amplitude  of  accommodation 
and  the  esophoria  would  both  throw  a  shadow  of  doubt  over  the 
accuracy  of  these  lenses. 

APPLICATION    OF    FOGGING    SYSTEM 

We  will  now  make  use  of  the  fogging  system  in  our  effort  to 
detect  some  of  the  hypermetropia  which,  we  think,  is  existing  in 
this  case  in  a  latent  form.  We  reduce  the  strength  of  the  convexes 
by  concaves,   until  now  we  have  a  plus  value  of  1   D.   before  the 


Hypermetropic  Astigmatism  Simulating  Myopic  23 

eyes,  with  which,  however,  vision  is  very  much  blurred  and  indis- 
tinct. Instead  of  reducing  still  further  with  concave  spheres,  we 
will  try  concave  cylinders  ;  placing  them  in  the  trial  frame  with  the 
position  of  the  axis  at  1800.  We  commence  with  a  —  .50  cyl. 
which  produces  an  immediate  improvement  in  vision  ;  we  try  suc- 
cessively a  —  .75  cyl.  and  a  —  1  cyl.  each  improving  over  the 
other,  and  the  latter  affording  a  vision  of  f$  full  and  f-£  partly. 
The  axis  of  the  cylinder  is  rotated  first  in  one  direction  and  then  in 
the  other,  but  patient  prefers  the  position  of  the  axis  at  1800  as 
affording  the  best  vision.  This  was  the  result  of  the  test  of  the 
right  eye,  and  on  the  left  eye  a  —  .75  cyL  was  preferred  with  axis 
at  1800.     Now  let  us  see  what  we  have  : 

O.  D.,  +  1  D.  sph.  O  —  1  D.  cyl.  axis  1800. 
O.  S.,  -4-  1  D.  sph.  O  —  .75  D.  cyl.  axis  1800 

Transposing  these  to  simpler  forms  we  get 

O.  D. ,  +  1  D.  cyl.  axis  900 

O.  S.,  +  .25  D.  sph.  O  -f-  .75  D.  cyl.  axis  900 

We  feel  now  that  we  have  worked  out  the  proper  correction, 
and  we  want  to  use  this  case  as  a  text  from  which  to  preach  a  short 
sermon  to  optometrists,  and  particularly  to  the  younger  and  less 
experienced  men  in  the  practice,  that  they  must  be  very  careful  not 
to  mistake  hypermetropia  for  myopia,  and  that  they  must  be  slow 
in  prescribing  concave  lenses,  unless  the  indications  for  them  are 
unmistakable. 

It  is  well  to  remember  that  in  the  great  majority  of  cases  that 
apply  to  you,  the  refraction  is  hypermetropic.  In  law,  a  man  is 
assumed  to  be  innocent  unless  he  is  proven  guilty.  In  optometry 
we  would  lay  down  and  establish  the  broad  general  principle  that 
the  error  of  refraction  in  any  case  that  applies  to  us  is  assumed  to 
be  hypermetropic  unless  there  is  positive  and  undeniable  proof  to 
the  contrary. 

We  are  not  likely  to  give  convex  lenses  when  myopia  is 
actually  present  ;  and  if  we  did.  no  great  harm  could  be  caused  by 
them.  But  we  are  likely  to  fall  into  the  error  of  giving  concave 
glasses  when  the  refraction  is  really  hypermetropic  (this  has  been 
done  over  and  over  again  by  men  who  should  know  better),  thus 
imposing  a  tax  on  the  accommodation  and  producing  a  condition 
of  asthenopia,  with  symptoms  of  great  discomfort. 


24  Clinics  in  Optometry 

Our  advice  in  cases  of  astigmatism,  or  in  any  case  where  there 
is  difficulty  in  determining  the  exact  condition  oi  refraction,  is  not 
to  prescribe  glasses  on  a  single  examination,  but  to  repeat  it  for  a 
third  time.  We  did  so  in  this  case  and  arrived  at  practically  the 
same  result  each  time,  but  we  did  not  think  it  wise  to  order  the  full 
correction  at  first,  therefore  we  compromised  on  the  following  : 

O.  U.,  -f  .50  D.  cyl.  axis  900 

These  lenses  were  prescribed  in  May,  1903,  and  have  given 
entire  satisfaction.  Patient  has  called  several  times  since  when 
lenses  were  broken,  and  always  speaks  in  the  highest  terms  of  bene- 
fits received  from  the  glasses. 


A    Case    in    Practice    with   Hysterical    Complication— Is 
Hysteria  the  Cause  or  the  Result  ? 


[Clinic  No.  4] 

Young  lady,  sixteen  years  of  age,  complains  of  headache. 
Applied  for  relief  two  years  ago,  at  which  time  she  was  wearing  -f 
.  50  D.  cyl.  axis  900  over  each  eye.  These  glasses  were  fitted  by 
an  oculist,  and  although  she  returned  to  him  twice,  complaining, 
he  announced  them  correct. 

She  states  that  in  addition  to  the  headache,  her  eyes  always 
ached  more  or  less,  and  that  artificial  light  was  extremely  trying  to 
them.  These  symptoms  were  aggravated  by  close  use  of  the 
eyes. 

An  intra-ocular  examination  showed  the  fundus  to  be  normal. 
Visual  acuteness,  O.  D.  f ,  O.  S.  f .  As  subjective  test  was  unsat- 
isfactory, reliance  was  placed  upon  the  retinoscope,  which  indicated 
a  hypermetropia  of  .75  D.  With  these  lenses  vision  of  each  eye 
singly  was  f ,  but  binocular  vision  was  £  clearly. 

These  glasses  were  prescribed  with  instructions  to  wear  con- 
stantly, and  to  report  in  one  month,  at  which  time  she  returned  and 
said  :  "Head  little  better,  but  still  have  trouble." 

An  examination  at  this  time  showed,  without  glasses,  O.  D.  £ 
?  ?,  O.  S.  £  ?  ?,  O.  U.  £.  +1  D.  was  indicated  by  the  ophthalmo- 
scope, with  which  vision  was  O.  D.  T\,  O.  S.  -fa,  O.  U.  £. 

Ophthalmometer  showed  an  overlapping  in  vertical  meridian  of 
about  half  step  in  both  eyes,  which  is  only  the  normal  amount  of 
excess  of  corneal  curvature. 

Muscle  tests  by  Maddox  rod  and  Maddox  double  prism  showed 
an  exophoria  of  40  at  distance,  and  of  8°  at  reading  point. 

-f  1  D.  was  prescibed  for  constant  wear.  In  two  weeks  she 
returned  and  said  :   "Headache  gone,  but  light  still  troubles  me." 

Muscles  were  retested  with  the  same  result  as  before,  and  as  a 
partial  correction  for  the  exophoria,  a  prism  of  i°,  base  in,  over 
each  eye  was  combined  with  the  spherical  correction.  These 
glasses  afforded  instant  relief  and  freed  her  from  the  asthenopic 
symptoms. 


26  Clinics  in  Optometry 

PHYSICIAN    DIAGNOSED    HYSTERIA 

In  six  months  she  came  back  with  the  following  statement  : 
She  had  been  vaccinated,  two  weeks  after  which  all  her  eye 
symptoms  returned  in  an  aggravated  form.  Another  examination 
was  made  and  finding  the  eyes  about  as  they  were  at  the  previous 
visit,  advised  the  lady  to  consult  a  physician,  who  pronounced  it  a 
case  of  hysteria,  with  various  symptoms  other  than  ocular,  for  which 
she  was  sent  to  the  hospital  for  treatment. 

Her  general  health  was  much  improved,  but  she  came  out 
of  the  hospital  still  suffering  with  the  head  trouble.  She  con- 
sulted the  optometrist  again,  and  as  another  examination 
revealed  nothing  further,  she  was  advised  to  apply  to  a  different 
oculist. 

Nothing  more  was  seen  of  her  until  January,  1904,  when  she 
affain  returned,  wearing  the  glasses  last  prescribed,  complaining  of 
headache  and  the  glasses  seeming  smoky.  An  examination  at  this 
time  showed  O.  D.  f,  O.  S.  f.  Retinoscopy  +  .50  D. ,  with  which 
vision  was  same  as  without  glasses. 

The  optometrist  consulted  now  was  very  much  surprised  to 
find  the  accommodation  was  lacking,  as  it  required  a  +  2.75  D. 
addition  to  distance  correction  to  enable  patient  to  read  at  14  inches, 
while  with  distance  glasses  alone  could  barely  read  1.75  D.  type  at 
35  cm. ,  and  that  for  a  moment  only. 

Muscle  tests  resulted  as  follows  :  At  20  feet,  30  exophoria  ; 
at  13  inches,  70  exophoria.  Adduction  190,  abduction  120.  The 
former  prescription,  +  1  D.  S.  Q  i°  prism,  base  in,  was  continued 
for  distance,  and  extra  fronts  containing  -f-  2.75  D.  given  her  for 
near  work. 

As  her  head  trouble  was  not  relieved,  he  concluded  that  the 
symptoms  originated  from  hysteria,  and  again  referred  her  to  a 
medical  specialist  for  treatment.  Atropine  was  prescribed,  but  as 
this  did  not  meet  his  sanction,  she  was  sent  to  another  oculist,  who 
said  she  did  not  need  glasses  and  advised  her  to  leave  them  off. 

After  two  months  she  returned  with  the  statement  that  her 
headaches  had  grown  steadily  worse.  Vision  now  was  only  yV  ; 
refraction  same  as  before,  but  the  glasses  afforded  no  improvement 
in  vision  as  they  previously  did. 

The  optometrist  is  fully  convinced  that  the  whole  is  due  to 
hysteria,   but  that  the  deterioration  of  vision  revealed  in  the  last 


A  Case  in  Practice  with  Hysterical  Complication  27 

examination  is  in  addition  partly  attributable  to  the  non-wearing  of 


WHAT   THIS    CASE   TEACHES 

We  will  study  this  case  together  as  it  stands  before  us,  and  see 
if  anything  practical  can  be  learned  from  it. 

We  are  not  quite  ready  to  agree  with  the  diagnosis,  but  grant- 
ing that  this  young  lady  is  hysterical,  is  hysteria  caused  by  the  eye- 
strain, or  to  reverse  the  question,  are  the  ocular  symptoms  the 
result  of  the  hysteria  ?  The  one  proposition  may  be  just  as  true  as 
the  other.  The  optometrist  seems  to  think  the  eye  symptoms  are 
caused  by  the  hysteria,  but  he  offers  no  arguments  to  prove  his 
position.  We  ask  why  may  not  the  hysteria  (if  such  exists),  be 
due  to  the  ocular  conditions  ?  At  any  rate,  we  think  the  proper 
plan  of  treatment  to  be  followed  is  a  more  determined  effort  to  cor- 
rect the  refractive  and  muscular  anomalies. 

All  that  was  done  for  the  exophoria  was  the  prescription  of  a 
pair  of  1  °  prisms.     Was  this  sufficient  ?     We  think  not. 

The  first  step  in  the  treatment  should  be  the  correction  of  any 
existing  error  of  refraction.  Now  it  must  be  remembered  that 
exophoria  is  usually  associated  with  myopia,  in  which  case  a  correc- 
tion of  the  latter  lessens  the  former.  Therefore,  if  concave  lenses 
lessen  exophoria,  convex  lenses  will  increase  it.  Now  the  lesson 
to  be  deduced  from  this  fact,  and  applied  in  the  case  before  us,  is  to 
give  the  convex  lenses  as  weak  as  possible,  because  the  stronger  the 
convex  lenses  that  are  worn,  the  greater  will  be  the  exophoria. 

This  fact  brings  out  another  feature  of  this  case,  viz.  :  that  the 
functions  of  accommodation  and  convergence  do  not  bear  their  nor- 
mal relation  to  each  other.  If  hypermetropia  was  present,  as  the 
tests  show,  and  if  accommodation  and  convergence  bore  their  cus- 
tomary close  relation,  the  accommodation  that  would  be  used  to 
overcome  the  hypermetropia  would  call  the  convergence  into  action 
and  produce  an  esophoria.  Instead,  in  this  case,  we  find  exo- 
phoria, which  complicates  the  case— makes  it  more  difficult  of  cor- 
rection, and  helps  to  account  for  the  asthenopic  symptoms. 

Therefore,  in  this  case,  we  would  not  prescribe  convex  lenses 
stronger  than  .  50  D. 

EXERCISE    BY    PRISMS 

The  next  step  in  the  treatment  is  to  make  an  effort  to  increase 
the  power  of  convergence,  which  in  this  case  is  relatively  weak. 


28  Clinics  in  Optometry 

This  is  to  be  accomplished  by  prismatic  exercise  of  the  internal 
recti  muscles.  The  strongest  prisms,  bases  out,  which  the  patient 
can  overcome,  and  maintain  singleness  of  vision,  should  be  placed 
in  a  frame  and  worn  for  several  minutes,  lifting  them  from  the  eyes 
occasionally  during  this  period  while  gazing  at  a  light  across  the 
room.  The  length  of  the  exercise  should  not  exceed  five  minutes, 
and  it  may  be  repeated  daily.  The  record  of  the  adduction  in  this 
case  is  19°,  but  it  can  probably  in  the  course  of  a  month  or  two  be 
trained  to  400  or  500,  by  a  gradual  increase  in  the  strength  of  the 
exercising  prisms. 

This  exercise  should  be  conducted  in  the  optometrist's  ofhce, 
in  connection  with  which  we  would  give  the  patient  a  pair  of  50 
prisms,  bases  out,  set  in  a  spectacle  frame  for  home  use,  with 
instructions  to  wear  from  fifteen  minutes  to  a  half  hour  each  day 
while  going  about  the  house. 

We  seldom  find  it  necessary  to  order  prisms  for  constant  wear 
in  exophoria  unless  of  much  higher  degree  than  this  case  ;  how- 
ever, as  the  i°  prisms,  bases  in,  afforded  so  much  relief  in  general 
vision,  the  optometrist  was  quite  justified  in  prescribing  them. 
But  as  exophoria  is  always  greater  at  the  reading  distance,  and  as  it 
is  always  increased  by  stronger  convex  lenses  (-f  3.75  being  now 
required  for  close  use),  it  follows  that  stronger  prisms  are  indicated 
for  the  reading  glasses,  and  therefore  the  extra  fronts  should  con- 
tain not  only  convex  spheres  but  prisms  as  well  ;  perhaps  +  3  D- 
sph.  C  prism  20,  base  in,  to  be  placed  over  the  -f  .50  D.  sphere, 
and  1  °  prism  worn  for  general  vision. 

After  the  optometrist  has  done  all  this,  that  is.  got  the  young 
lady  started  on  this  line  of  optometric  treatment,  she  may  be  refer- 
red to  the  medical  man  for  supplemental  treatment,  which  would 
probably  consist  of  general  or  nerve  tonics. 

If,  under  the  influence  of  this  combined  treatment,  the 
power  of  convergence  is  increased,  as  we  have  reason  to 
expect,  we  may  reasonably  look  for  relief  from  the  symptoms 
complained  of,  in  which  case  we  will  be  able  to  reduce  the 
reading  prisms. 

The  effect  of  the  exercise  with  prisms,  bases  out,  which  calls 
the  convergence  so  strongly  into  action,  will  also  through  their  close 
nervous  correction,  have  a  stimulating  and  beneficial  action  on 
the  ccommodation,  which  seems  to  be  too  weak  to  perform  its 
function. 


A  Case  in  Practice  with  Hysterical  Complication  29 

EYE    MANIFESTATION    OF    HYSTERIA 

Let  us  for  a  moment  consider  what  ocular  symptoms  usually 
result  from  hysteria. 

There  may  be  twitching  and  spasmodic  closure  of  the  lids  with 
spasm  of  accommodation  ;  in  our  case  the  accommodation  is  relaxed, 
or  perhaps  paralyzed  ;  therefore  there  is  nothing  in  this  symptom 
to  indicate  hysteria  ;  in  fact  it  rather  tends  to  contra-indicate  it. 

The  visual  disorders  that  are  found  in  connection  with  hysteria 
vary  from  a  slight  impairment  of  vision  to  total  blindness.  Hyster- 
ical amblyopia  comes  on  suddenly,  the  ophthalmoscopic  appear- 
ances being  negative.  Both  eyes  may  be  affected,  but  more  fre- 
quently the  trouble  is  monocular.  The  vision  is  unexpectedly 
improved  by  any  kind  of  lenses — convex,  concave  or  even  pris- 
matic— acting  in  all  probability  through  the  imagination.  Hysteri- 
cal amblyopia  does  not  usually  last  long,  and  disappears  as  suddenly 
as  it  came. 

These  symptoms  do  not  correspond  very  closely  with  those  of 
the  case  under  consideration,  and  therefore  we  conclude  that  this  is 
not  a  typical  case  of  hysteria,  and  that  the  nervous  symptoms  are 
more  likely  the  result  of  the  eye  troubles  than  the  cause  of  them. 

This  young  lady  should  be  advised  to  disregard  and  ignore  her 
eye  symptoms  :  not  to  allow  her  mind  to  dwell  on  them,  but  to 
keep  it  occupied  with  other  things  to  the  exclusion  of  her  eyes.  In 
other  words,  her  eye  symptoms  will  never  improve  as  long  as  her 
mind  dwells  on  them  ;  while  they  are  much  more  likely  to  disap- 
pear if  she  can  forget  them. 


A  Typical  Case  of  Hypermetropia 


[Clinic  No.  5] 

R.  S.  C. ,  aged  nineteen  years,  a  hat  finisher  by  occupation. 
Complains  of  headache  which  comes  on  about  noon  every  day 
except  Sundays.  This  symptom  is  a  striking  one  and  indicates  at 
once  that  the  headache  is  due  to  eyestrain. 

At  first  on  going  to  work  in  the  morning,  the  ciliary  muscle 
which  had  been  refreshed  and  invigorated  by  the  previous  night's 
sleep,  is  easily  able  to  overcome  the  refractive  error  and  afford 
good  vision  without  any  apparent  effort.  But  after  a  while  this 
continued  tax  on  the  accommodation,  which  is  so  much  greater 
than  it  should  be  normally,  begins  to  cause  fatigue  and  by  the  time 
the  noon  hour  is  reached  the  eye  is  sending  vigorous  complaints  to 
headquarters  (the  brain),  that  the  burden  of  work  imposed  upon  it 
is  in  excess  of  its  natural  capacity.  This  is  simply  and  solely  what 
the  headache  means. 

The  normal  eye,  as  is  the  case  with  every  other  organ  in  health, 
performs  its  function  without  our  consciousness.  As  soon  as  the 
eye  complains,  in  other  words,  as  soon  as  feelings  of  discomfort 
remind  us  that  we  have  eyes,  there  is  evidence  that  they  are  not  as 
they  should  be,  that  something  is  wrong.  These  warnings  must  be 
heeded,  and  they  are  by  the  prudent  man  ;  if  disregarded,  the 
trouble  grows  worse  and  the  condition  of  the  eyes  may  become 
serious. 

DIAGNOSING    THE   CASE 

So  far  we  have  this  symptom  of  headache  following  use  of  the 
eyes,  and  we  naturally  think  of  hypermetropia  or  hypermetropic 
astigmatism.  We  ask  our  patient  what  letters  are  legible  on  the 
distant  test  card,  and  we  find  that  the  acuteness  of  vision  in  each  eye 
is  f£.  This  is  so  much  better  than  normal  that  it  practically 
excludes  astigmatism. 

In  the  further  determination  of  this  point,  we  make  ophthal- 
mometric  examination,  and  find  that  the  mires  overlap  one-half 
step  in  the  vertical  meridian  in  each  eye.  This  corresponds  to  the 
normal  corneal  curvature,  and  is  corroborative  of  the  opinion 
expressed  a  moment  ago  that  the  error  is  not  one  of  astigmatism. 


A  Typical  Case  of  Hypermetropic!,  31 

This  leaves  hypermetropia  as  the  probable  condition  of  refrac- 
tion, and  in  order  to  determine  its  existence  we  place  convex  lenses 
before  the  eyes  as  the  patient  views  the  distant  test  card,  and  we 
find  that  +  1  D.  lenses  are  readily  accepted,  thus  indicating  a 
manifest  hypermetropia  of  this  amount. 

The  hypermetrope  (if  not  too  old  and  if  the  error  is  not  of  too 
high  degree)  usually  sees  well  at  a  distance,  in  fact  he  oftentimes 
enjoys  an  unusual  degree  of  acuteness  of  vision.  Such  a  person, 
in  view  of  his  remarkable  vision,  is  apt  to  laugh  at  the  suggestion 
of  a  defect  in  his  eyes,  and  the  thought  of  glasses  is  to  him  little 
less  than  ridiculous. 

We  proceed  now  to  examine  our  patient's  near  vision  and 
measure  his  amplitude  of  accommodation.  We  find  that  he  can 
read  the  small  print  as  close  as  5  inches  and  as  far  away  as  27 
inches  ;  this  near  point  of  5  inches  represents  an  amplitude  of 
accommodation  of  8  D.  Now  how  does  this  compare  with  the  nor- 
mal standard  ? 

In  any  treatise  on  eye  refraction  will  be  found  a  table 
showing  the  amount  of  amplitude  of  accommodation  that 
should  be  present  at  the  different  stages  through  life.  Every 
case  must  be  gaged  by  comparison  with  this  table,  and  in  this 
way  any  departure  from  the  standard  at  any  given  age  can  be- 
readily  detected. 

At  twenty  years  of  age  the  eye  should  possess  10  D.  of  ampli- 
tude of  accommodation  ;  our  patient  at  nineteen  possesses  only  8 
D.  of  accommodation.  There  is,  therefore,  an  evident  deficiency 
of  2  D.  at  least,  and  a  presumption  of  the  existence  of  hypermetro- 
pia of  like  amount. 

It  will  be  remembered  that  in  hypermetropia  distinct  distant 
vision  is  possible  only  by  an  effort  of  accommodation  equal  in 
amount  to  the  grade  of  defect,  and  hence  in  close  vision  there  is  a 
deficiency  of  like  amount.  Therefore,  in  this  young  man's  case 
when  we  find  that  the  accommodation  at  the  near  point  is  2  D.  less 
than  it  should  be,  we  are  justified  in  assuming  that  this  amount  of 
accommodation  has  been  used  to  overcome  hypermetropia  and 
render  distant  vision  clear. 

This  examination  of  the  amplitude  of  accommodation  cor- 
roborates our  diagnosis  of  hypermetropia,  and  shows  it  to 
be  even  greater  than  the  acceptance  of  the  convex  lenses  has 
indicated. 


32  Clinics  in  Optometry 

CORROBORATIVE   TESTS 

Continuing  our  examination,  we  look  into  the  condition  of  the 
muscular  equilibrium.  We  use  the  Maddox  rod  and  place  it 
over  the  left  eye  in  a  horizontal  position.  The  image  formed  in 
this  eye  is  a  vertical  streak  of  light,  which  our  patient  tells  us  is 
about  six  inches  to  the  left  of  the  light.  This  is  a  condition  of 
homonymous  diplopia,  due  to  an  over  convergence  of  the  eyes,  and 
indicates  esophoria.  After  trying  several  prisms,  we  find  that  one 
of  40  base  out  brings  the  red  streak  directly  through  the  flame. 
This  esophoria  which  we  have  discovered  in  this  way,  is  additional 
corroborative  evidence  of  the  presence  of  hypermetropia ;  because 
the  latter,  by  calling  the  accommodation  into  play,  also  stimulates 
the  convergence  ;  and  hence,  unless  there  is  some  disturbance  of 
the  relation  that  closely  binds  the  functions  of  accommodation  and 
convergence,  esophoria  always  accompanies  hypermetropia. 

Our  next  step  in  the  examination  is  to  try  each  eye  separately 
with  the  test  lenses,  and  inasmuch  as  the  lessened  amplitude  of 
accommodation  indicates  a  degree  of  hypermetropia  greater  than 
the  convex  lenses  previously  accepted,  we  will  make  use  of  the 
fogging  method. 

We  place  +  5  D.  in  the  trial  frame  in  front  of  the  right  eye. 
Patient  says  he  cannot  see  a  single  letter  on  the  test  card.  We 
hold  a  —  .50  D.  in  front  of  the  +  5  D.,  and  patient  says  the  card 
looks  clearer,  but  he  is  still  unable  to  name  any  letters.  We 
replace  the  —  .50  D.  by  a  —  1  D.  and  now  patient  is  able  to  see 
the  large  letter  at  the  top  of  the  test  card.  We  gradually  increase 
the  strength  of  the  concave  at  first  by  —  .50  D.  and  then  by  —  .25 
D. ,  until  finally  patient  is  able  to  name  all  the  letters  on  the  No.  20 
line  and  most  of  them  on  the  No.  15  line. 

Now,  we  will  see  what  we  have  in  the  trial  frame.  In  the  back 
cell  we  have  the  +  5  D.  lens  which  was  originally  placed  there. 
In  the  front  cell  we  have  —  2.50  D.  The  latter  neutralizes  half  of 
the  former,  and  leaves  a  plus  value  in  front  of  the  eyes  of  2. 50  D. , 
with  which  patient  has  normal  vision,  and  therefore  we  have  dis- 
covered or  unearthed  a  hypermetropia  of  this  amount. 

The  convex  lens  causes  the  rays  of  light  to  enter  the  eye  in  a 
convergent  condition.  A  hypermetropic  eye  (with  suspended 
accommodation)  is  adapted  for  convergent  rays,  in  fact  there  is  no 
other  form  of  eye  in  which  convergent  rays  can  focus  on  the  retina ; 


A  Typical  Case  of  Hypermetropia  33 

therefore,  when  a  patient  can  see  at  a  distance  through  convex 
lenses,  in  other  words,  when  convergent  rays  can  be  received 
by  an  eye,  hypermetropia  is  proven  to  exist,  and  theoretically 
the  degree  of  convergence  will  correspond  to  the  amount  of 
hypermetropia. 

Of  course,  it  is  understood  that  the  accommodation  is 
capable  of  making  the  entering  rays  convergent,  and  thus  focus- 
ing them  on  the  retina.  But  this  places  a  burden  on  the  cil- 
iary muscle,  for  which  nature  never  intended  it ;  thus  causing 
the  headache  and  other  asthenopic  symptoms  ;  and  it  is  the 
duty  of  the  optometrist  to  ascertain  if  the  accommodation  is 
subjected  to  such  unnatural  strain,  and  if  so.  to  take  the  proper 
means  to  relieve  it. 

We  now  test  the  left  eye  in  the  same  way  by  the  fogging 
method,  and  we  find  that  when  a  —  3D.  is  placed  in  front  of  the 
fogging  lens  of  +  5  D. ,  that  normal  acuteness  of  vision  is  secured, 
thus  indicating  a  hypermetropia  of  2  D. 

We  will  finish  our  examination  of  this  young  man's  eyes  with 
the  retinoscope,  which,  I  am  glad  to  say,  gives  us  the  same  results 
as  found  by  the  fogging  method. 

DIAGNOSIS   VERIFIED 

We  now  have  a  complete  record  of  this  case,  and  as  all  tests 
agree,  we  have  no  difficulty  in  arriving  at  a  satisfactory  diagnosis  of 
the  nature  of  the  defect  and  the  amount.  This  being  done,  it 
might  seem  at  first  thought  that  a  pair  of  lenses  O.  D.  -J-  2.50  ;  O. 
S.  -f  2,  should  be  prescribed,  to  the  instant  relief  and  satisfaction 
of  the  patient. 

But  the  experience  of  the  writer  has  been,  that  it  is  not  well  to 
try  to  force  too  strong  a  convex  lens  on  a  young  eye  that  has  never 
been  accustomed  to  wearing  glasses.  It  will  blur  distant  vision  and 
make  the  eye  uncomfortable ;  of  course,  if  the  use  of  the  glasses  is 
persisted  in  for  several  months,  the  impairment  of  vision  and  feeling 
of  discomfort  will  gradually  disappear  ;  but  very  few  patients  are 
willing  to  wear  glasses  in  the  face  of  such  disadvantages.  When 
glasses  are  put  on,  the  patient  naturally  expects  to  see  better  ;  he 
thinks  that  is  the  purpose  for  which  glasses  are  worn.  If,  on  the 
other  hand,  vision  is  impaired  by  the  glasses,  the  impulse  of  the 
patient  is  to  take  them  off,  and  it  is  only  exceptionally  that  he  can 
be  persuaded  to  wear  them  under  such  circumstances. 


34  Clinics  in  Optometry 

For  these  reasons,  in  this  case,  where  patient  is  young  and 
accommodation  is  vigorous,  we  will  correct  only  half  the  error  and 
order  glasses  as  follows  : 

O.  D.,  +  1.25  D.  ;  O.  S.,  +  1  D. 

When  patient  made  a  report  later  we  were  told  that  these 
glasses  have  relieved  the  headache  and  afforded  entire  satisfaction. 
Whereas,  if  we  had  attempted  to  give  a  full  correction,  patient 
would  have  returned  most  likely  very  much  dissatisfied,  when  we 
would  have  been  compelled  to  reduce  the  strength  of  the  glasses,  or 
patient  would  have  wandered  off  to  some  other  optometrist,  of  more 
tact  if  not  of  more  skill.  Why,  then,  shouldn't  we  prescribe  the 
weaker  glasses  first,  and  thus  maintain  our  reputation  and  retain 
the  patient's  confidence? 


A  Case  of  Toxic  Amblyopia  from  Alcohol  and  Tobacco 


[Clinic  No.  6] 

The  case  we  now  present  for  your  consideration  is  a  man,  51 
years  of  age,  a  quarryman  by  occupation.  He  was  sent  to  us  by 
a  most  capable  refractionist  to  whom  he  applied  for  glasses,  and 
who  realized  at  once  that  the  case  was  out  of  the  ordinary  and  that 
glasses  were  of  doubtful  benefit  in  the  present  condition  of  his  eyes. 

The  patient  tells  us  that  his  eyes  feel  heavy,  that  his  vision  has 
been  failing  for  some  time,  and  that  for  the  past  four  weeks  he  has 
been  unable  to  read,  without  glasses  or  with  them. 

We  ask  the  man  to  look  at  the  test  card  hanging  across  the 
room,  and  we  find  the  acuteness  of  vision  of  the  right  eye  is  TW> 
while  with  the  left  eye  he  is  unable  to  decipher  even  the  largest 
letter  at  the  top  of  the  card. 

THE    PIN-HOLE   TEST 

In  order  to  determine  whether  this  impairment  of  vision  is  due 
to  ametropia,  or  whether  it  depends  upon  a  condition  of  disease, 
we  will  make  use  of  the  pin-hole  disk.  It  has  the  effect  of  reduc- 
ing the  circles  of  diffusion  formed  upon  the  retina,  and  thus  makes 
the  outlines  of  objects  much  clearer. 

On  account  of  the  smallness  of  the  opening,  it  diminishes  the 
illumination,  but  this  loss  of  light  is  more  than  compensated  for  by 
the  greater  clearness  of  form  that  is  attained. 

If  the  vision  is  susceptible  of  improvement  by  this  test,  glasses 
will  be  of  benefit.  If  the  vision  cannot  be  improved  by  the  pin- 
hole, glasses  are  useless.  This  test  is  one  that  can  always  be 
depended  upon. 

By  cutting  off  all  the  marginal  rays  and  allowing  only  a  few  of 
the  more  central  rays  to  fall  upon  the  retina,  the  eye  is  rendered 
independent  of  its  refracting  media,  in  fact,  their  function  is  des- 
troyed, and  the  image  is  formed  solely  by  the  few  central  rays  that 
pass  through  the  small  opening.  The  image  thus  being  made  per- 
fect ;  if  now  the  vision  still  continues  impaired,  it  must  be  because 
the  retina  is  not  capable  of  receiving,  or  the  optic  nerve  of  trans- 
mitting, this  image. 


36  Clinics  in  Optometry 

Any  capable  refractionist  can  demonstrate  this  for  himself. 
Take  any  kind  or  power  of  lens  from  your  test  case,  convex  or  con- 
cave, weak  or  strong,  sphere  or  cylinder,  hold  it  close  to  your  eye 
and  look  through  it  at  the  test  letters  ;  vision  will  be  made  more  or 
less  indistinct  according  to  the  strength  and  character  of  the  lens, 
but  no  matter  how  greatly  the  letters  are  blurred  or  even  if  blotted 
out  of  sight,  when  the  pin-hole  disk  is  placed  over  it,  the  power  of 
the  lens  is  destroyed,  and  the  letters  are  as  clearly  seen  as  with  the 
emmetropic  eye. 

We  will  now  see  what  the  results  of  this  test  are  :  vision  of 
right  eye  is  little  if  any  improved.  Vision  of  left  eye  is  raised  to 
f$  with  some  difficulty.  This  proves  that  the  impairment  of  vision 
in  R.  E.  is  not  susceptible  of  any  improvement  by  lenses,  while  L. 
E.  is  only  partially  so.  This  is  a  very  great  diminution  in  vision 
and  would  also  indicate  his  inability  to  read  fine  print.  We  give 
him  the  test  card  in  his  hand,  and  as  we  expected,  he  says  he  is 
unable  to  read  any  of  the  paragraphs.  As  a  matter  of  routine,  we 
try  successively  +  I,  +  2,  +  3,  +  4  and  -f  5,  but  with  none  of 
them  is  he  able  to  read  anything  except  the  larger  sized  print  at  the 
bottom  of  the  card. 

QUESTIONING   THE    PATIENT 

We  will  take  this  man  into  our  dark  room  and  make  an 
ophthalmoscopic  examination.  The  reflex  is  clear  and  bright 
proving  that  there  are  no  opacities  in  any  of  the  refracting  media. 
The  optic  disk  looks  a  little  paler  than  normal  with  perhaps  a 
bluish  or  greenish  tinge,  otherwise  no  evidence  of  the  presence 
of  disease. 

We  will  question  this  man  as  to  his  personal  habits.  ' '  Do 
you  drink  or  smoke?"  "Yes,  sir."  "Now  tell  us  the  truth, 
how  much  do  you  drink?  Tell  these  gendemen  just  what  your 
habits  are  in  this  direction."  "Every  evening  on  my  way  home 
from  work  I  stop  in  the  saloon  and  take  a  drink  of  whisky  and  wash 
it  down  with  a  mug  of  beer.  I  spend  Saturday  evening  there  when 
I  take  from  three  to  four  to  half-a-dozen  drinks." 

"  As  this  is  a  matter  of  importance  to  your  welfare,  you  must 
not  conceal  anything,  and  I  am  glad  you  have  given  us  such  a  frank 
answer.      Now  how  about  tobacco  ? ' ' 

"  I  smoke  both  cigars  and  a  pipe,  and  am  seldom  without  one 
or  the  other  in  my  mouth." 


A  Case  of  Toxic  Amblyopia  from  Alcohol  and  Tobacco       37 

The  very  candid  statement  of  this  patient  clears  up  the  case, 
and  I  think  we  can  unhesitatingly  diagnose  this  condition  as  one  of 
toxic  amblyopia  due  to  the  excessive  use  of  alcohol  and  tobacco  ; 
and  as  you  are  likely  to  meet  with  similar  cases  in  your  future  prac- 
tice, we  will  direct  this  patient  to  be  seated  while  we  give  a  few 
moments'  time  to  the  consideration  of  this  condition. 


The  Perimeter 


Tobacco  and  alcohol  cause  disturbances  of  vision  with  nearly 
identical  symptoms.  Either  one  may  produce  the  disease,  but 
usually  both  are  combined  in  the  same  case.  It  seldom  occurs  in 
young  persons,  the  patients  usually  being  over  40  years  and  with 
impaired  nutrition.  We  find  it  more  among  the  poorer  classes 
because  poor  whisky  contains  more  fusel  oil  and  cheap  tobacco 
more  nicotine. 

While  the  ophthalmoscope  gives  no  certain  evidence  as  to  the 
presence  of  the  disease  in  its  early  stages,  yet  as  a  rule  it  is  not 
difficult  of  diagnosis,  because  of  the  pronounced  subjective 
symptoms. 

CHARACTERISTIC    SYMPTOMS 

A  failure  of  vision  is  noticed,  most  marked  in  the  center  of  the 
field.     Usually  both  eyes  are  affected,  but  not  always  to  the  same 


38  Clinics  in  Optometry 

extent.  The  patient  sees  nothing  directly  in  the  line  of  vision,  but 
objects  on  either  side  are  seen  with  more  or  less  distinctness.  This 
interferes  with  reading  and  writing,  although  if  the  scotoma  is  not 
large,  while  the  middle  of  the  sentence  is  lost  the  two  ends  of 
the  line  may  be  seen  imperfectly.  Patients  usually  complain  more 
of  disturbance  of  vision  when  in  a  bright  light.  Vision  for  color 
also  fails  in  this  central  scotoma,  the  perception  of  red  and  green 
being  lost. 

As  we  look  at  our  patient  he  has  the  appearance  of  a  naturally 
healthy  man,  but  no  one  can  drink  beer  and  whisky  as  he  does 
and  continue  it  with  impunity.  Some  men  may  drink  more,  and 
because  they  have  not  yet  lost  their  sight  or  ruined  their  stomach, 
they  think  they  are  all  right.  Some  men  may  go  through  a  battle 
without  being  shot,  and  yet  no  one  will  argue  that  war  is  a  safe 
occupation.  So  any  man  that  uses  alcohol  and  tobacco  to  excess 
is  in  danger  that,  sooner  or  later,  some  organ  will  give  out. 

Is  there  a  scotoma  in  this  case  ?  In  order  to  determine  this 
point  we  will  send  for  a  perimeter  and  make  the  test  before  you. 
We  will  use  a  piece  of  red  card,  and  we  find  as  it  approaches  the 
center  of  the  field,  it  disappears,  and  be  it  remembered  this  is  one 
of  the  diagnostic  points  of  a  toxic  amblyopia,  the  scotoma  for  red  in 
the  center  of  the  field.  We  may  remark  in  passing  that  as  the 
patient  begins  to  recover  and  the  scotoma  becomes  less  noticeable, 
the  patient  first  sees  red  as  pink,  and  gradually  as  improvement 
continues  it  becomes  redder  and  darker. 

THE    PERIMETER 

We  are  sometimes  asked  by  students  about  to  enter  on  prac- 
tice, whether  a  perimeter  should  be  included  in  their  outfit,  and  we 
usually  answer  that  we  do  not  consider  it  necessary,  adding  a  few 
words  of  explanation  as  to  the  specific  uses  of  the  instrument.  It 
consists  essentially  of  an  arc,  as  you  see,  which  can  be  moved  to 
any  position  in  order  to  measure  any  desired  meridian,  and  a  small 
white  test  object  moved  in  from  its  outer  end  until  it  becomes  visible. 
As  this  is  repeated  at  a  number  of  different  points,  say  150  or  200 
apart,  until  the  circle  is  completed,  the  outlines  of  the  field  are 
indicated.  The  test  object  is  also  moved  inward  to  the  center 
along  the  different  meridians  and  in  this  way  the  presence 
of  any  scotomata  are  detected,  and  their  size  and  location  are 
mapped  out. 


A  Case  of  Toxic  Amblyopia  from  Alcohol  and  Tobacco        39 

The  province  of  the  perimeter  then  is  to  measure  the  field  of 
vision  and  to  detect  the  existence  of  a  scotoma,  all  of  which  is 
included  in  indirect  vision.  It  has  little  to  do  with  direct  vision, 
the  vision  of  the  yellow  spot  in  which  you  are  particularly  inter- 
ested in  fitting  glasses,  and  therefore  it  is  only  in  exceptional  cases 
that  you  will  even  think  of  it. 

If  you  consider  in  any  case  it  is  desirable  to  obtain  some  idea 
of  the  extent  of  the  field  of  vision,  it  can  be  determined  on  the 
blackboard  or  any  plane  surface.  A  mark  is  made  for  the  sight  to 
be  fixed  upon,  and  a  piece  of  chalk  is  moved  inwards  from  the 
extreme  limits  of  the  board  up  to  the  center.  The  marks  made 
where  it  first  appears  indicate  the  limits  of  the  field.  If  it  should 
disappear  and  reappear,  a  scotoma  would  be  shown  to  exist. 

Now,  it  is  safe  to  say  the  diagnosis  has  been  fairly  made  out. 
The  patient  cannot  see  well,  his  vision  does  not  respond  to  the  pin- 
hole nor  to  any  lenses  we  place  before  his  eyes,  proving  that  it  is 
not  an  error  of  refraction  ;  there  is  no  opacity  or  any  disease  of  the 
retina  ;  there  is  the  scotoma  for  red  in  the  center  of  the  field  ;  he  is 
an  inordinate  user  of  alcohol  and  tobacco. 

The  first  step  in  the  treatment  is  the  removal  of  the  cfause, 
and  if  this  man  wants  to  regain  his  sight,  he  must  abstain  from 
drinking  and  smoking.  In  addition  we  will  prescribe  strychnia 
internally,  galvanism  locally  and  a  good  nourishing  diet. 

INSTRUCTIONS    TO    PATIENT 

To  the  patient,  "My  man,  for  the  sake  of  your  sight  and  for 
the  benefit  of  your  family  that  depends  upon  you,  you  must  cut  out 
your  beer,  whisky  and  tobacco.  If  you  will  faithfully  follow  our 
directions,  I  think  I  can  safely  promise  that  you  will  get  well. 
Come  back  in  a  week  and  report. ' ' 

Note  that  in  this  case  the  prognosis  is  good,  and  so  it  is  in  any 
case  of  toxic  amblyopia  if  patient  is  seen  early  and  if  he  will  abstain 
entirely  from  the  poisonous  agents.  He  may  even  get  well  if  he  is 
willing  only  to  reduce  their  quantity,  but  this  is  not  at  all  certain 
Persistence  in  their  use  is  sure  to  lead  to  greater  impairment  of 
vision  or  even  practical  blindness.  After  complete  recovery,  the 
disease  may  sometimes  recur  if  the  appetite  for  drinking  and  smok- 
ing is  uncurbed. 

While  it  scarcely  comes  within  your  province  to  prescribe  the 
administration  of  a  nerve  tonic  or  the  application  of  electricity,  yet 


40  Clinics  in  Optometry 

I  think  it  is  your  duty  as  educated  optometrists  to  be  able  recog- 
nize the  existence  of  this  condition,  and  it  will  also  add  greatly  to 
your  prestige.  Make  your  examination  along  the  lines  I  have 
mentioned,  and  refer  your  patient  to  a  medical  man  for  treatment. 
In  this  way  you  establish  a  reputation  for  competency  with  the 
patient  and  his  physician,  and  you  gain  the  good  will  and  confi- 
dence of  both. 

Three  weeks  later  we  have  before  us  this  same  patient  but  a 
great  change  has  taken  place.  He  has  called  each  week  since  then, 
always  reporting  improvement.  He  says  his  eyes  have  lost  that 
heavy  feeling  and  that  they  feel  good.  We  test  his  vision  on  the 
card  and  find  that  with  +1.50  the  acuity  equals  -|£.  He  says  in 
answer  to  our  question  that  he  has  not  drank  any  whisky  or  beer, 
but  that  he  has  smoked  an  occasional  cigar.  This  is  a  very  satis- 
factory improvement  and  the  indications  point  to  complete  recovery. 
We  will  advise  him  that  his  welfare  demands  continued  abstinence, 
and  that  he  should  still  keep  on  with  the  medicine  and  the  galvan- 
ism for  some  weeks  longer. 


A  Case  of  Refactive  Error  Diagnosed  as  Cataract 


[Clinic  No.  7] 

The  case  we  have  to  present  for  consideration  on  this  occasion 
is  an  interesting  one,  that  points  a  moral  not  only  in  the  diagnosis 
between  disease  and  refractive  error,  but  in  the  technique  of  the 
examination  of  doubtful  cases. 

Mr.  J.W.  L. ,  aged  thirty-eight  years,  has  been  advised  to  con- 
sult us  by  the  optican  who  fitted  him  with  glasses,  on  account  of  cata- 
ract in  the  left  eye.  This  gentleman  whom  we  know  to  be  a  compe- 
tent optometrist,  sends  this  note  with  patient,  in  which  he  says  he 
has  fitted  right  eye  with  —  .50  cyl.  axis  1800,  and  left  eye,  because 
of  cataract,  is  fitted  indifferently  with  a  weak  convex  sphere. 

We  will  glance  at  this  patient's  eyes,  but  we  look  in  vain  for 
any  noticeable  evidence  of  cataract.  A  casual  examination  shows 
that  the  pupil  of  the  left  eye  is  just  as  bright  and  black  as  that  of  the 
right  eye.  This  at  once  disproves  the  diagnosis  of  cataract, 
because  in  this  disease,  if  at  all  advanced,  the  pupil  becomes  white 
or  whitish  gray.  This  grayish  appearance  is  so  diagnostic  of  cata- 
ract, that  sometimes  opticians  (and  the  laity,  too)  class  leucoma 
(a  gray  opacity  of  the  cornea)  as  cataract,  a  mistake  which  every 
intelligent  man  will  want  to  avoid. 

WHAT    A    CATARACT    IS 

As  cataract  is  a  condition  which  you  will  not  uncommonly  meet 
in  your  practice,  it  is  proper  that  you  should  have  a  well-defined 
idea  of  just  what  it  is  and  how  you  will  determine  its  presence. 

Cataract  is  an  opacity  of  the  cystalline  lens.  It  is  not  a  tumor 
or  a  growth  of  any  kind,  but  it  is  simply  a  condition  in  which  the 
crystalline  lens  loses  its  transparency  and  becomes  opaque.  The 
lens  instead  of  being  transparent  as  in  health,  becomes  translucent. 
Remember,  this  milky  appearance  is  in  the  lens,  not  in  the  cornea  ; 
it  is  behind  the  iris,  not  in  front  of  it.  When  an  eye  presents  this 
gray  color,  don't  hastily  conclude  that  the  patient  is  suffering  from 
cataract.  Examine  the  eye  closely,  and  if  you  find  this  milky 
appearance  located  in  the  corneal  tissue,  the  case  is  one  of  leucoma, 
which  is  a  very  different  thing  from  cataract. 


42  Clinics  in  Optometry 

If  you  find  the  cornea  of  normal  transparancy,  which  you  can 
determine  by  simply  looking  at  it,  or  still  better,  by  oblique  illumi- 
nation, and  if  the  milky  appearance  occupies  the  pupil  and  back  of 
the  iris,  the  trouble  is  undoubtedly  cataract. 

In  order  to  demonstrate  this,  I  will  ask  the  patient  to  be  seated 
on  a  chair  beside  the  light,  and  I  take  a  strong  convex  lens  from 
the  trial  case  and  focusing  the  light  on  the  anterior  portion  of  the 
eye,  we  see  the  cornea  and  aqueous  are  transparent  and  the  pupil 
free  from  opacity. 

If  the  cataract  is  complete,  it  will  be  readily  recognized  in  the 
manner  I  have  outlined.  In  incipient  cataract  before  the  whole  lens 
has  become  affected,  the  partial  opacity  is  best  detected  by  the 
ophthalmoscope,  using  a  strong  convex  lens  in  the  sight  hole  and 
holding  the  instrument  about  the  focal  distance  of  this  lens  from  the 
eye. 

I  will  rotate  a  +  6  D.  lens  into  the  aperture  of  my  ophthal- 
moscope, and  approaching  to  about  6l/>  inches,  I  find  a  perfect  red 
reflex,  unobstructed  by  the  slightest  opacity.  This  completely  dis- 
poses of  the  diagnosis  of  cataract,  but  so  far  we  have  shed  no  light 
on  the  cause  of  the  impaired  vision. 

CAUSE   OF    IMPAIRED   VISION 

We  ask  the  patient  how  long  his  eye  has  been  so  bad,  and  he 
tells  us  that  it  has  been  so  to  his  certain  knowledge  for  fifteen  years, 
and  perhaps  longer.  It  has  caused  him  no  great  inconvenience, 
and  he  assumed  that  nothing  could  be  done  for  it. 

We  place  the  black  rubber  disk  over  right  eye  and  direct 
patient's  attention  to  the  card  of  test  letters.  He  can  see  there  is 
something  there,  but  he  cannot  see  that  it  is  a  card,  much  less  dis- 
cern any  marks  on  it. 

Will  some  of  you  who  are  following  this  clinic,  tell  me  what 
should  be  the  first  step  in  the  examination  of  this  eye  in  order  to 
determine  its  optical  condition?  "The  use  of  the  pin-hole  test," 
you  reply  ;  yes,  that  is  correct.  In  this  way  we  can  quickly  deter- 
mine whether  or  not  any  vision  is  present,  and  if  so,  whether  it  will 
respond  to  our  test  lenses. 

The  pin-hole  disk  is  placed  in  trial  frame  before  the  eye,  and 
patient  begins  to  name  the  larger  letters  :  he  commences  at 
the  top  and  names  the  letters  on  the  first  four  lines.  This  cor- 
responds  to  a  visual  acuity  of    f$,   and  we  will    make  a  note   to 


A  Case  of  Refractive  Error  Diagnosed  as  Cataract  43 

this  effect  in  our  record  book.  We  now  know  that  there  must 
be  a  considerable  error  of  refraction  present,  and  that  by  its 
measurement  we  must  be  able  to  improve  vision  at  least  to  an 
equal  amount. 

Before  commencing  our  test  with  trial  lenses,  we  will  ask  the 
patient  to  step  over  to  the  ophthalmometer  table  and  see  what  light 
this  instrument  will  throw  upon  the  case.  First,  you  must  focus 
the  instrument  so  as  to  secure  the  sharpest  possible  reflection. 
Then  approach  the  mires  until  they  barely  touch  each  other  in  the 
horizontal  position.  Now,  we  will  slowly  rotate  the  instrument  and 
note  the  result. 

As  the  instrument  is  turned  the  mires  at  once  begin  to  overlap 
each  other,  until  as  the  vertical  meridian  is  reached,  there  is  an 
overlapping  of  1,  2,  3,  4,  5,  6  steps  ;  yes,  six  full  steps.  What 
does  this  indicate?  It  shows  a  corneal  astigmatism  of  6  D.,  the 
curvature  of  the  vertical  meridian  exceeding  the  horizontal  by  that 
amount  ;  or  the  horizontal  falling  below  the  normal  curvature  to  an 
equal  extent. 

Now,  how  shall  we  classify  this  astigmatism  ?  It  is  either 
hypermetropic  astigmatism  in  the  horizontal  meridian,  or  myopic 
astigmatism  in  the  vertical  meridian,  or  a  combination  of  both. 

THE    TRIAL    CASE    EXAMINATION 

We  will  now  proceed  with  our  trial  case  examination.  As  the 
case  seems  so  overwhelmingly  one  of  astigmatism,  we  will  try  first 
a  cylinder  instead  of  a  sphere,  as  we  usually  do  ;  but  we  will  not 
depart  from  our  rule  of  always  trying  convex  first.  As  the  astig- 
matism is  evidently  of  high  degree,  it  seems  useless  to  try  a  weak 
lens,  and  so  we  will  commence  with  a  +  3  D.  cylinder,  which, 
according  to  the  indications  of  the  ophthalmometer,  we  place  in 
trial  frame  with  axis  vertical. 

The  patient  says  this  affords  no  improvement  ;  in  fact,  makes 
vision  worse  if  anything.  We  feel  disappointed  because  the  pin- 
hole showed  that  vision  could  be  improved,  and  as  the  ophthalmo- 
meter revealed  such  a  high  degree  of  corneal  astigmatism,  we 
assumed  the  correction  of  the  latter  would  cause  the  looked-for 
improvement  in  vision. 

However,  before  discarding  this  lens  we  will  rotate  it,  and  as 
we  do  so,  we  are  rather  surprised  to  find  that  vision  begins  to 
improve,  reaching  its  best  point  when  axis  is  horizontal. 


44  Clinics  in  Optometry 

This  shows  a  case  of  astigmatism  against  the  rule  ;  whereas, 
the  reading  of  the  ophthalmometer  showed  astigmatism  with  the 
rule.  But  the  latter  measures  only  the  corneal  astigmatism,  while 
the  lens  corrects  the  total  defect,  which  is  made  up  of  both  corneal 
and  lenticular  astigmatism.  Therefore,  we  must  conclude  that  the 
defect  in  the  crystalline  lens  not  only  neutralizes  that  in  the  cornea, 
but  turns  it  in  the  other  direction. 

LIMITATIONS    OF   THE   OPHTHALMOMETER 

Now,  I  would  not  for  an  instant  belittle  the  value  of  the 
ophthalmometer  ;  I  would  not  part  with  mine,  and  I  would  advise 
all  of  you  that  can  afford  it  to  procure  one  ;  but  at  the  same  time 
we  must  admit  that  in  many  cases  its  readings  are  not  to  be 
depended  upon,  and  this  particular  case  is  one  of  them. 

As  the  patient  notices  a  decided  improvement  in  vision  with 
the  convex  cylinder,  and  as  he  unhesitatingly  prefers  the  axis  in 
the  horizontal  position,  we  feel  that  we  have  at  last  struck  the  right 
track,  which  we  must  follow  to  its  best  results. 

We  therefore  gradually  increase  the  strength  of  the  cylinder, 
producing  still  greater  improvement,  until  finally  we  reach  -f  6  D. 
cyl.  axis  1800,  which  is  the  strongest  patient  will  accept,  and  with 
which  the  larger  letters  on  test  card  are  now  readable. 

As  vision  is  not  yet  up  to  the  standard  set  by  the  pin-hole,  we 
know  that  we  have  not  reached  the  proper  correction  and  we  must 
make  still  further  effort.  With  the  thought  that  perhaps  the 
astigmatism  is  not  fully  corrected,  we  will  try  a  concave  cylinder 
over  this  convex  with  its  axis  at  right  angles,  commencing  with  a 
—  i  D.  Patient  says  the  addition  of  this  lens  affords  a  marked 
improvement,  and  we  increase  its  strength  until  we  reach  —  6  D.  cyl. 

We  now  have  in  the  trial  frame  +  6  D.  cyl.  axis  i8o°  Q  —  6 
D.  cyl.  axis  900,  and  we  will  ask  the  patient  to  name  letters  on 
lowest  line  he  can  see.  He  says  C  B  L  O  T  G  ;  you  will  recognize 
this  as  the  No.  30  line,  half  of  the  letters  being  incorrectly  named. 
We  will  make  note  in  our  record  book  that  with  the  cross-cylinder 
correction  V.  —  \%  ?  ?  ?,  the  interrogation  points  denoting  that 
three  of  the  letters  were  in  doubt.  Now  this  is  a  pretty  good  result 
for  an  eye  that  was  diagnosed  cataractous  and  given  up  as  prac- 
tically blind. 

But  our  difficulties  are  not  yet  over  by  any  means  :  it  is  one 
thing  to  correct  a  high  degree  of  defect,  and  it  is  another  to  get  the 


A  Case  of  Refractive  Error  Diagnosed  as  Cataract  45 

patient  to  wear  such  a  lens  in  a  case  where  the  other  eye  is  so 
nearly  normal.  And,  by  the  way,  we  must  ascertain  its  acuteness 
of  vision  and  its  correcting  lens,  if  any.  We  find  that  V.  =  f$ 
almost,  some  of  the  letters  being  in  doubt.  After  trying  convex 
spheres  and  cylinders,  we  find  that  —  .25  D.  cyl.  axis  200,  affords 
the  greatest  acuteness  of  vision,  and  makes  every  letter  of  the  No. 
20  line  perfectly  plain. 

We  try  the  two  eyes  together,  each  with  its  correction,  but 
patient  says  that  objects  are  doubled  and  the  glasses  are  so  confus- 
ing that  he  could  not  wear  them,  We  must,  therefore,  reduce  the 
strength  of  the  left  lens,  and  after  several  trials  patient  seems  to  be 
able  to  bear 

O.  D.,  —  .25  cyl.  axis  200 

O.  S.,  +  4  cyl,  axis  1800  Q  —  4  cyl.  axis  900. 

and  this  is  the  prescription  we  will  give  him  for  constant  wear. 

For  near  vision,  patient  must  have  full  correction,  and  hence 
we  will  give  him  another  prescription,  as  follows  : 

O.  D.,    Frosted 

O.  S.,  +  6  D.  cyl.  axis  1800  Q-6D.  cyl.  axis  900. 

With  this  cross  cylinder  left  eye  is  able  to  read  the  finest  print, 
but  because  of  the  fact  that  there  has  never  been  a  perfect  image 
formed  in  this  eye,  the  sensibility  of  the  retina  is  blunted.  This  we 
will  endeavor  to  overcome  by  directing  patient  to  use  these  glasses 
"  for  exercise  "  about  fifteen  or  twenty  minutes  each  day,  selecting 
print  that  is  not  too  small. 

We  will  advise  this  gentleman  that  he  must  have  patience, 
that  there  will  be  some  difficulty  in  the  use  of  both  pairs  of  glasses, 
but  that  the  restoration  of  the  sight  of  this  heretofore  useless  eye  is 
worth  all  the  trouble  he  may  be  caused. 


Compound  Hypermetropic  Astigmatism  and  Presbyopia, 

Showing  when  Cylinders  May  and  Should 

be  Omitted  From  Reading  Glasses 


[Clinic  No.  8] 

Mrs.  Elizabeth  B. ,  aged  sixty-six  years,  complains  that  sight  is 
dim,  eyes  water,  and  lids  are  sometimes  agglutinated  in  the  morn- 
ings. We  ask  her  if  she  has  ever  worn  glasses.  She  replies  that 
she  has,  and  hands  us  her  glasses,  which  we  find  by  neutralization 
to  be  +  2.50  D.  for  distance,  and  +  4.50  D.  for  reading. 

We  request  her  to  be  seated,  and  on  directing  her  attention  to 
the  test  card  hanging  at  twenty  feet,  she  tells  us  she  is  unable  to 
name  any  of  the  letters. 

METHOD    OF    EXAMINATION 

In  accordance  with  established  custom  we  commence  the 
examination  with  convex  lenses,  starting  with  -f  1  D.  This  at 
once  improves  vision  and  makes  the  larger  letters  readable.  We 
increase  +  .50  D.  at  a  time  until  we  reach  -f-  2.50  D. ,  with  which 
she  can  name  a  few  of  the  letters  on  the  No.  20  line.  An  additional 
-f-  .50  D.  affords  no  further  improvement,  in  fact,  she  thinks  makes 
it  worse. 

We  will  now  try  +  .  50  D.  cyl.  over  the  +  2. 50  D.  S. ,  which 
we  place  in  the  trial  frame  in  the  position  customary  for  convex 
cylinders,  viz.,  with  axis  at  900.  This  she  at  once  rejects,  but 
before  we  remove  the  lens  we  will  try  the  effect  of  rotation.  As 
we  turn  it  slowly  around  she  tells  us  there  is  some  improvement, 
which  reaches  its  maximum  when  axis  is  horizontal.  The  addition 
of  this  cylinder  enables  her  to  read  all  the  letters  on  the  No.  20  line, 
and  we  will  make  the  following  note  in  our  record  book  : 

O.  D.  with  +  2.50  D.  S.  C  +  -50  cyl.  axis  1800.     Vision  frfc. 

We  remove  the  cylinder  in  order  to  give  her  an  opportunity  to 
compare  vision  without  it  and  with  it,  and  she  unhestatingly  states 
that  she  can  see  much  better  with  it.  We  will  now  proceed  to 
examine  the  other  eye  in  the  same  way,  and  we  find  that  it  accepts 
the  same  combination,  which  therefore  represents  the  refractive 
error  in  each  eye.     For  reading  we  find,  after  a   few  trials,  that 

46 


Compound  Hypermetropic  Astigmatism  and  Presbyopia        47 

-f  5  D.  S.  is  the  best  with  which  she  gets  the  clearest  vision 
at  fourteen  inches.  The  addition  of  the  cylinders  that  were 
accepted  for  distance  affords  no  improvement,  in  fact,  patient 
says  she  can  read  better  without  them. 

EXCEPTIONAL   CASES 

Now,  why  should  this  cylinder  be  rejected?  If  astigmatism 
exists,  is  it  not  proper  to  correct  it  in  any  glasses  that  may  be 
placed  before  the  eyes,  both  for  reading  and  distance  ?  This  has 
always  been  the  teaching,  and  the  majority  of  us  in  our  practice, 
and  perhaps  I  may  say  all  of  us,  have  followed  this  custom.  I 
shall  not  attempt  to  deny  the  soundness  of  this  as  a  general  prin- 
ciple, but  I  will  point  out  to  you  the  class  of  cases  in  which  we 
must  make  an  exception,  and  this  lady  will  serve  as  our  text  for 
that  purpose. 

In  the  first  place,  I  want  to  say  that  the  majority  of  persons 
who  furnish  these  exceptions  to  the  general  rule  are  those  who  have 
reached  or  passed  middle  age  ;  in  other  words,  presbyopes  who  in 
addition  have  both  curvature  and  axial  ametropia.  Such  persons 
require  a  sphere  and  cylinder  for  general  vision,  the  axis  of  the  lat- 
ter being  horizontal,  and  in  addition  a  somewhat  strong  spherical 
lens  for  near  vision. 

There  must  be  a  good  optical  reason  for  this  departure  from 
custom,  and  we  will,  therefore,  give  some  consideration  to  the  mat- 
ter. All  of  you  are  aware  of  the  fact  that  when  rays  of  light  pass 
through  a  convex  sphere  they  are  converged  to  a  point,  in  such 
cases  it  being  understood  that  the  light  strikes  the  lens  at  right 
angles  to  its  surface.  But  perhaps  you  are  not  so  thoroughly 
familiar  with  the  fact  that  when  the  rays  of  light  pass  obliquely 
through  the  lens,  they  are  not  all  converged  to  a  point.  A  tilting 
of  the  lens,  or  an  obliquity  of  the  rays,  introduces  a  cylindrical  effect, 
and  then  the  light  rays  are  acted  on  as  if  passing  through  a  sphero- 
cylindrical lens  held  with  its  surface  at  right  angles  to  the  rays. 

Let  us  see  if  we  can  prove  the  truth  of  this  assertion.  I  will 
take  a  —  2D.  lens  and  place  it  in  the  trial  frame  before  the  right 
eye  and  the  opaque  disk  before  the  left  eye.  I  place  the  trial  frame 
on  my  face  and  hold  a-f  2D.  lens  before  my  right  eye.  The  con- 
vex lens  neutralizes  the  concave,  and  my  sight  is  the  same  as  with 
the  naked  eye.  I  look  at  the  card  of  radiating  lines,  and  they  all 
look  equally  black  and  plain. 


48  Clinics  in  Optomeiry 

Now,  I  will  begin  to  tilt  the  convex  lens  vertically,  moving  the 
upper  part  of  this  lens  away  from  the  concave  ;  in  other  words, 
tilting  the  lens  on  its  horizontal  axis.  As  I  do  so  I  notice  the  hori- 
zontal lines  lose  a  little  in  clearness,  the  vertical  remaining  as  plain 
as  before.  The  more  I  tilt  the  lens  the  dimmer  the  horizontal  lines 
become,  and  not  only  the  horizontal  but  the  oblique  lines,  until 
finally  they  are  all  blurred  and  indistinct,  except  only  the  vertical, 
which  still  retain  their  original  clearness. 

PHENOMENA    OBSERVED    BY    TILTING 

As  the  convex  lens  is  tilted  around  its  horizontal  axis  the  con- 
verging power  of  the  vertical  meridian  is  increased,  while  that  of 
the  horizontal  meridian  is  but  little  affected.  The  refractive  power 
of  the  lens  is  now  the  same  as  if  a  convex  cylinder  had  been  placed 
before  the  sphere  with  its  axis  horizontal.  Therefore,  the  rays  of  light 
passing  through  the  vertical  meridian  are  brought  to  a  focus  sooner 
than  those  passing  through  the  horizontal  meridian.  In  other 
words,  the  focal  distance  of  the  vertical  meridian  is  less  than  that  of 
the  horizontal. 

How  do  these  facts  apply  to  the  lines  as  we  have  just  seen 
them  ?  It  will  be  remembered  that  the  distinctness  of  the  vertical 
lines  depends  upon  the  proper  curvature  of  the  horizontal  meridian 
of  the  eye,  while  the  horizontal  lines  bear  the  same  relation  to  the 
vertical  meridian  of  the  eye.  Therefore,  as  the  refractive  power  of 
the  vertical  meridian  of  the  lens  is  increased  by  tilting,  the  hori- 
zontal lines  are  brought  to  a  focus  before  reaching  my  retina,  and 
are  consequently  blurred  and  indistinct,  while  the  vertical  lines 
passing  through  the  horizontal  meridian  (which  is  not  affected  by 
the  tilting)  retain  their  original  clearness. 

Now,  let  us  see  what  we  have — a  convex  sphero-cylinder,  with 
the  axis  of  the  latter  at  1800,  or  as  applied  to  my  eye,  an  artificial 
myopic  astigmatism  with  the  rule,  the  excess  of  curvature  being 
vertically.  The  next  question  that  occurs,  how  can  it  be  neutralized 
or  corrected?  Obviously,  in  the  sphero-cylindrical  combination, 
the  cylindrical  effect  is  neutralized  by  a  concave  cylinder  with  axis 
in  same  position,  viz.,  horizontal  ;  while  the  artificial  myopic  astig- 
matism is  corrected  by  the  same  form  of  cylinder  and  in  same 
position. 

Now,  I  will  repeat  my  experiment  and  make  use  of  this  cor- 
recting cylinder.      As  I  tilt  the  convex  sphere  and  notice  that  the 


Compound  Hypermetropic  Astigmatism  a?id  Presbyopia       49 

horizontal  lines  have  become  indistinct,  I  hold  a  —  .50  D.  cyl.  axis 
1800  in  front  of  the  convex  lens,  and  in  vertical  position — that  is, 
parallel  to  the  concave  sphere  in  the  trial  frame.  This  at  once  cor- 
rects the  artificial  astigmatism,  clears  the  lines  and  make  them  all 
equally  black  and  distinct. 

If  I  tilt  the  convex  lens  more  I  will  need  stronger  and  stronger 
concave  cylinders  to  neutralize  the  increased  convex  effect  of  the 
vertical  meridian  and  maintain  the  lines  equally  clear.  As  there  is 
nothing  like  practical  demonstration,  I  will  ask  you  gentlemen  to 
try  this  experiment  for  yourselves,  so  that  you  can  see  the  added 
cylindric  effect  caused  by  the  tilting  of  the  sphere;  and  the  neutrali- 
zation of  the  same  by  a  corresponding  concave  cylinder.  Those  of 
you  who  are  not  emmetropic  will  need  to  put  in  the  trial  frame 
your  own  correction,  and  then  proceed  as  I  have  indicated. 

THE    LESSON    TO    BE    LEARNED 

Now,  what  is  the  lesson  to  be  learned  from  this,  and  what 
application  can  we  make  of  it  in  our  practice  ? 

In  the  first  place  every  person  who  wears  convex  lenses  for 
reading,  or  writing,  or  sewing,  develops  a  cylindrical  addition  to 
their  lenses  more  or  less  marked  according  to  their  strength  and  the 
degree  of  obliquity  of  the  visual  axis.  The  stronger  the  lenses  and 
the  greater  the  obliquity  the  more  marked  the  cylindric  effect. 

In  the  second  place,  in  cases  of  low  degree  of  astigmatism,  in 
which  the  axis  of  the  correcting  cylinder  is  horizontal,  the  latter 
may  be  omitted  from  the  reading  glasses  because  the  same  effect  is 
produced  by  the  obliquity  of  the  rays  passing  through  the  sphere, 
and  if  the  cylinder  was  retained  the  astigmatism  would  be  over  cor- 
rected. I  will  repeat  that  this  does  not  apply  to  lenses  for  constant 
wear  in  persons  under  forty  years  of  age,  nor  to  simple  cylinders 
with  axis  vertical,  but  the  principle  is  applicable  to  persons  over 
forty,  who  are,  therefore,  presbyopic,  and  whose  distant  vision  calls 
for  a  convex  sphero-cylinder  axis  horizontal,  or  even  simple  cylin- 
ders axis  horizontal. 

This  patient  is  a  typical  case  for  the  application  of  this  prin- 
ciple. The  +  5  D.  spherical  lenses  which  she  requires  for  near  use 
will  produce  a  cylindrical  effect  at  least  equal  to  her  astigmatism  at 
distance.  It  has  been  estimated  that  a  -f  1  D.  sphere,  as  usually 
worn  for  reading,  produces  a  cylindrical  effect  of  .125  D. ,  and  this 
would  afford  in  our  case  an  added  cylinder  of  .  62  D.  or  an  eighth 


50  Clinics  in  Optometry 

diopter  more  than  we  really  need.  We  will,  therefore,  prescribe  for 
this  lady  : 

R.  and  L.,  +  2.50  D.  S.  Q  -f-  .50  D.  cyl.  axis  1800  for 
distance  and  general  wear,  and  R.  and  L,  +  5  D.  S.  for  read- 
ing, in  the  knowledge  that  the  latter  pair  as  used  for  reading, 
even  though  simple  spheres,  will  afford  just  as  much  cylindric 
power  as  those  for  distance,  which  are  ground  both  spherical  and 
cylindrical. 

I  have  no  hesitation  in  advising  you  to  follow  these  suggestions 
in  your  practice  when  you  meet  cases  similar  to  this  one  under  con- 
sideration to-day.  If  the  astigmatism  is  of  low  degree  the  cylinder 
may  be  omitted  entirely  as  in  this  lady's  case.  If  the  astigmatism 
is  of  higher  degree  the  cylinder  may  be  reduced  in  accordance  with 
the  estimate  given  you  a  few  moments  ago,  viz. ,  —  .  25  D.  for  each 
2  D,  of  spherical  power.  You  thus  under-correct  the  astigmatism 
by  cylinders,  which  is  then  made  up  by  the  increased  converging 
power  of  the  vertical  meridian  of  the  tilted  spherical  lens,  or  rather 
the  lens  remaining  straight  by  the  oblique  direction  of  the  visual 
axes. 

For  sake  of  illustration,  if  we  have  an  eye  that  requires  -j-  1 
D.  S.  O  +  .25  D.  cyl.  axis  1800  for  distance,  and  an  additional 
-\-  1  D.  for  reading,  we  would  prescribe  +  2  D.  S.  for  reading, 
omitting  the  cylinder,  but  securing  the  effect  of  the  same  by  the 
oblique  direction  of  the  visual  axes  in  reading. 

If  we  had  a  patient  whose  error  of  refraction  was  represented 
by  +  2  D.  S.  O  -f-  1  D.  cyl.  axis  1800,  with  2  D.  of  presbyopia 
in  addition,  we  would  prescribe  for  reading,  -f  4  D.  S.  Q  +  .50 
axis  1800,  correcting  half  of  the  astigmatism  by  the  cylinder,  and 
getting  the  correction  of  the  other  half  by  the  increase  in  power  of 
the  vertical  meridian  of  the  sphere.  You  will  meet  numerous  cases 
in  your  practice  in  which  you  can  act  on  these  suggestions  with 
results  satisfactory  to  yourself  and  your  patients. 

In  my  remarks  about  this  case,  and  in  the  illustrations  I  have 
used,  I  have  referred  particularly  to  convex  lenses,  but  you  will  see 
that  the  same  principles  apply  to  concaves,  viz.,  the  increase  in 
power  of  the  vertical  meridian  of  a  spherical  lens  when  the  rays  of 
light  pass  through  it  obliquely. 

While  I  have  spoken  only  of  horizontal  and  vertical  meridians 
and  axes,  I  might  say  that  those  cases  may  be  included  where  the 
meridians  are  within  io°  of  these  cardinal  lines. 


Compound  Hypermetropic  Astigmatism  and  Presbyopia        51 

POINTS   TO    BE    REMEMBERED 

Before  closing  our  clinics  for  to-day  perhaps  I  ought  to  say 
that  if  the  person  wears  spectacles  and  the  temples  are  purposely 
bent  angular,  so  as  to  give  the  lenses  the  proper  degree  of  obliquity, 
then  of  course,  the  conditions  are  changed  and  the  cylindrical  effect 
of  the  lenses  is  not  made  apparent.  Also  with  the  users  of  eye- 
glasses, which  are  so  frequently  worn  with  the  tops  of  the  lenses 
tilted  forward,  these  remarks  do  not  apply.  In  these  cases  the  tilt- 
ing of  the  lens  places  it  at  right  angles  to  the  visual  axis  and  cor- 
rects any  tendency  to  cylindrical  effect,  while  in  the  experiments  to 
which  I  called  your  attention  a  few  moments  ago,  when  the  visual 
axis  is  directed  straight  forward  to  distance,  the  tilting  of  the  lens 
produces  an  obliquity  of  the  rays. 

I  feel  that  I  have  presented  to-day  for  your  consideration  some 
thoughts  that  are  perhaps  new  to  many  of  you,  and  which  all  of 
you  can  think  over  with  profit.  These  suggestions  do  not  have  a 
wide  range  of  application,  as  this  class  of  cases  forms  only  a  small 
proportion  of  the  total  with  which  you  have  to  deal,  but  they  will 
surely  be  of  advantage  in  properly  selected  cases,  and  may  enable 
you  to  understand  your  failure  to  give  satisfaction  in  some  cases 
where  the  cause  of  the  trouble  was  obscure,  and  help  you  to  a  more 
scientific  and  comfortable  correction  than  would  be  possible  by  an 
optometrist  who  was  ignorant  of  the  principles  which  I  have 
attempted  to  make  clear. 


Presbyopia 

[Clinic  No.  9] 

You  will  be  called  upon  in  your  practice  to  prescribe  glasses 
for  presbyopia  more  frequently  than  for  any  other  form  of  visual 
defect.  Perhaps,  however,  we  should  modify  this  statement  or, 
rather,  state  it  in  a  different  way  :  Presbyopia  undoubtedly  heads 
the  list  of  the  forms  of  eye  failure  for  which  glasses  are  sought,  but 
very  many  presbyopes  purchase  their  glasses  as  they  do  an  article 
of  merchandise.  They  are  loath  to  believe  that  their  eyes  are 
defective.  They  say  that  their  eyes  have  always  been  good 
until  quite  recently,  and  they  think  perhaps  they  are  strained, 
or  cold  has  settled  in  them,  and  they  will  be  all  right  in  a  feu- 
days. 

But  finally  the  patient  begins  to  realize  that  the  impairment  of 
close  vision  is  permanent,  and  he  drops  into  a  spectacle  store  and 
asks  for  a  pair  of  ' '  rest  glasses, "  or  "  first  glasses. ' '  He  does  not 
feel  the  need  of  a  thorough  examination  of  his  eyes,  and  therefore 
as  you  are  all  skilled  refractionists,  he  does  not  seek  your  services, 
and  for  this  reason  your  record  books  will  perhaps  not  show  as 
large  a  proportion  of  cases  of  presbyopia  as  the  frequency  of  this 
defect  would  indicate. 

Presbyopia  is  one  of  the  penalties  of  age.  You  have  learned 
from  your  studies  that  certain  changes  take  place  in  the  eye  with 
the  advance  of  years,  all  of  which  tend  to  make  more  difficult  the 
act  of  accommodation. 

This  presbyopic  change  is  no  respecter  of  persons  ;  it  occurs 
in  all  classes  of  society  and  in  the  eyes  of  every  person  who  reaches 
middle  age.  The  evidence  of  it  is  influenced  by  the  refractive  con- 
dition of  the  eye,  being  accentuated  in  hypermetropia,  while  in 
myopia  it  is  less  noticeable.  This  brings  out  the  fact  that  every  per- 
son who  lives  the  allotted  span  of  life  is  called  upon  to  wear  glasses 
al  some  time  or  other  during  his  life.  The  evidence  is  around  us 
on  every  hand  that  many  children  and  young  people  must  wear 
glasses  :  but  those  who  perchance  escape  at  this  time,  find  them- 
selves up  against  it  in  the  "forties,"  when  reading  and  near  work 
become  less  and  less  possible  without  artificial  assistance. 


Presbyopia  53 

ILLUSTRATIVE    CASES    OF    PRESBYOPIA 

Inasmuch  as  this  condition  of  presbyopia  is  so  common,  it  may 
not  prove  unprofitable  for  us  to  devote  our  clinic  hour  to-day  to  its 
consideration,  and  illustrate  it  by  several  cases  that  have  presented 
themselves  for  examination. 

Mr.  G.  P.  L.,  aged  forty-four  years,  complains  of  headache 
after  reading,  or  any  close  use  of  eyes. 

When  a  person  of  this  age  complains  of  difficulty  in  close  use 
of  eyes,  we  at  once  suspect  presbyopia.  But  as  educated  opto- 
metrists, we  have  no  right  to  proceed  to  prescribe  glasses  on  this 
assumption,  but  we  must  prove  or  disprove  it. 

In  the  first  place  we  determine  the  acuteness  of  vision.  We 
ask  the  patient  to  read  the  lowest  line  of  letters  on  the  test  card, 
and  he  names  every  one  on  the  No.  20  line.  This  being  normal 
vision  excludes  myopia,  and  in  order  to  determine  the  possibility  of 
hypermetropia,  or  slight  hypermetropic  astigmatism,  we  try  a  + 
.50  sphere  and  a  +  .50  cylinder,  rotating  the  latter  through  the 
different  meridians.  Both  of  these  being  rejected,  we  are  justified 
in  concluding  that  the  refraction  is  emmetropic. 

We  now  hand  the  patient  the  reading  card,  and  ask  him  if  he 
can  read  the  smallest  type  at  the  top  of  the  card.  He  replies  that 
he  can,  at  the  same  time  moving  the  card  away  from  his  eyes.  We 
request  him  to  bring  the  card  nearer,  as  close  to  his  eyes  as  it  is 
possible  for  him  to  make  out  the  words  even  though  he  feels  it  a 
great  strain,  and  on  measuring  this  distance  we  find  it  to  be  nine 
inches,  which  represents  the  near  point  in  this  case,  thus  indicating 
a  deficiency  of  accommodation. 

The  question  occurs  as  to  what  is  the  standard  by  which  the 
accommodation  must  be  gaged  ?  The  least  amount  of  accommoda- 
tion which  an  eye  should  possess  in  order  to  use  the  eyes  for  close 
vision  without  strain,  is  5  D.,  and  therefore  in  this  patient's  case 
there  is  a  deficiency  of  accommodation. 

Now  we  have  the  essential  features  of  this  case  as  follows  : 

Refraction,  normal. 
Accommodation,  deficient. 
Age,  forty-four  years. 

The  existence  of  these  three  factors  in  any  one  case  proves 
presbyopia.  If  any  one  is  missing,  it  cannot  be  simple  presbyopia  ; 
and  when  all  are  present,  it  cannot  be  anything  else. 


54  Clinics  in  Optometry 

You  will  doubtless  meet  with  cases  in  which  the  refraction  is 
apparently  normal,  but  with  deficiency  of  accommodation,  in  per- 
sons who  are  less  than  forty  years  of  age.  Such  patients  cannot 
be  presbyopic,  although  they  are  often  wrongly  classed  as  such. 
If  the  refraction  is  carefully  examined  (as,  for  instance,  by  the 
fogging  method  and  by  skiascopy)  it  will  be  found  that  the 
refraction  is  hypermetropic,  showing  itself  as  a  so-called  early 
presbyopia. 

Many  optometrists  in  their  examination  of  cases,  assume  that 
the  refraction  is  normal  when  they  find  the  acuteness  of  vision  to 
equal  f$.  But  you  must  not  too  hastily  jump  to  such  a  conclusion, 
else  you  will  oftentimes  overlook  hypermetropia  and  hypermetropic 
astigmatism. 

WHAT    GLASSES    TO    PRESCRIBE 

We  are  safe  then  in  diagnosing  this  case  as  one  of  presbyopia, 
and  now  the  question  occurs  as  to  what  glass  should  be  prescribed  ? 
Theoretically,  this  is  a  simple  matter  :  the  eye  should  possess  5  D. 
of  accommodation,  this  man  has  only  4.50  D.  (as  shown  by  the 
near  point  of  nine  inches),  and  the  deficiency  is  therefore  .50  D., 
which  is  made  up  by  a  convex  lens  of  like  amount. 

We  will  ask  this  man  if  he  has  ever  worn  glasses.  He  replies 
that  he  got  a  pair  about  six  months  ago,  but  they  "  pulled  his  eyes 
and  he  hasn't  worn  them  much."  We  ask  to  see  the  glasses,  and 
on  neutralizing  them  find  them  to  be  -f-  1  D. 

According  to  the  slight  impairment  of  the  accommodation 
shown  by  our  examination,  you  will  say  that  these  glasses  are  too 
strong,  and  this  has  been  proved  by  our  patient's  experience  with 
them. 

In  the  commencement  of  presbyopia  it  is  not  well  to  give 
glasses  too  strong  at  first.  It  is  a  fact  that  should  guide  you  in 
your  selection  of  glasses,  that  there  is  much  more  complaint  from 
glasses  too  strong  than  from  those  too  weak. 

We  will  therefore  order  +  .50  D.  lenses  for  this  man  for  close 
work  only,  with  every  confidence  that  they  will  prove  satisfactory. 

The  next  patient  is  S.  W.  B.,  aged  forty-five  years,  who  com- 
plains that  for  the  past  year  he  has  had  difficulty  in  reading,  especi- 
ally at  nights. 

We  find  the  acuteness  of  vision  in  each  eye  is  *&,  and  that  con- 
vex lenses  are  positively  rejected.  This  proves  the  refraction  to  be 
emmetropic. 


Presbyopia  55 

We  give  him  the  card  of  small  type,  and  he  cannot  read  the 
first  or  the  second  size.  He  can  read  only  the  third,  and  that  no 
closer  than  fifteen  inches. 

We  have  now  all  the  essentials  for  a  diagnosis  of  presbyopia  : 
emmetropic  eyes,  deficient  accommodation  and  age  over  forty. 

COMMON    SENSE    VERSUS    THEORY 

Now  what  glasses  shall  we  order  in  this  case  ?  The  near  point 
of  fifteen  inches,  and  that  with  no  smaller  type  than  No.  3,  indi- 
cates an  amplitude  of  accommodation  of  not  more  than  2.50  D., 
which  is  just  one-half  of  what  a  person  should  possess  for  comfort- 
able reading.  In  this  case,  therefore,  a  glass  of  -f-  2.50  D.  is  theo- 
retically required  to  bring  the  accommodation  up  to  the  standard 
of  5  D.  Shall  we  prescribe  so  strong  a  glass  for  a  person  who  has 
heretofore  never  worn  glasses  ?  No,  it  would  scarcely  be  proper. 
We  cannot  tie  ourselves  down  to  any  hard  and  fast  rules.  They 
must  be  modified  to  suit  individual  cases,  and  we  must  make  use  of 
common  sense  and  good  judgment  all  the  time. 

With  the  knowledge  that  strong  glasses  cause  more  discomfort 
than  weak  ones,  we  would  not  dare  in  this  case  to  give  first  glasses 
of  +  2.50  D. 

Without  any  special  rule  to  guide  us  in  the  selection  of  glasses 
in  such  conditions,  but  relying  on  our  experience  in  similar  cases, 
we  will  order  +  1  D.  lenses  for  close  use  to  begin  with.  This  man 
has  been  reading  up  to  the  present  time  without  any  help  at  all  ;  if 
we  assist  him  to  the  extent  of  +  1  D.  it  will  be  pleasantly  received. 
But  if  we  offer  him  too  much  help,  if  we  over-assist  him,  discomfort 
will  result  and  the  glasses  will  be  rejected. 

Our  third  and  last  case  in  to-day's  clinic  is  I.  B.  J.,  aged  forty- 
nine  years,  who  acknowledges  to  some  difficulty  in  reading. 

The  acuteness  of  vision  is  •§-§-,  and  all  convex  lenses  are  rejected. 

Of  course,  you  will  notice  we  are  testing  his  distant  vision  with 
the  lenses,  and  when  we  say  all  convex  lenses  are  rejected  it  is 
understood  at  twenty  feet,  as  the  examination  of  the  condition  of 
the  refraction  must  be  made  with  rays  of  light  that  are  as  nearly  as 
possible  parallel. 

On  testing  the  near  vision  we  find  that  patient  cannot  see  the 
No.  1  type,  but  he  reads  No.  2  as  close  as  twelve  inches. 

We  now  have  the  three  factors  on  which  the  diagnosis  of 
presbyopia  rests. 


56  Clinics  in  Optometry 

What  glasses  shall  we  give  this  man  ?  His  amplitude  of  accom- 
modation is  3. 25  D. ,  as  shown  by  the  near  point  of  twelve  inches, 
therefore  he  needs  +  1.75  D.  glasses  to  bring  his  accommodative 
power  up  to  the  standard  of  5  D.  '  But  is  it  wise  to  give  him  glasses 
as  strong  as  this  ?  Remember  he  has  never  worn  glasses,  and  if  we 
give  him  +  1.75  D.  the  crutch  will  probably  be  too  high  for  com- 
fort. He  has  been  so  long  accustomed  to  stooping  over  that  he 
cannot  bear  being  raised  to  the  upright  standard  all  at  once.  We 
will  therefore  prescribe  -f  1  D.  for  close  use  in  the  confidence  that 
they  will  afford  more  satisfaction  than  the  stronger  lenses  which  are 
seemingly  indicated. 

SUMMARY    OF    RESULTS 

Perhaps  you  will  have  noticed  that  all  three  of  the  cases  have 
been  handled  differently. 

In  the  first  case  (G.  P.  L. )  we  gave  the  full  correction  as  indi- 
cated by  the  rule,  viz. ,  to  supply  such  glasses  that,  added  to  the 
amplitude  of  accommodation,  will  equal  5  D.  We  were  justified  in 
this  by  the  age  of  the  patient,  and  that  even  the  full  correction  was 
a  comparatively  weak  glass,  as  weak  as  would  be  of  any  special 
value.  This  man's  accommodation  is  but  little  impaired,  but  he 
shows  wisdom  in  seeking  optical  help  as  soon  as  he  feels  the  need 
of  it,  instead  of  struggling  for  awhile  against  the  inevitable  as  the 
other  two  have  done. 

In  the  second  case  (S.  W.  B. )  we  gave  less  than  half  the  indi- 
cated correction.  We  were  guided  in  this  selection  not  only  by  the 
fact  of  these  being  the  first  glasses,  but  because  of  the  age  of  the 
patient,  being  only  five  and  forty.  It  is  possible  his  glasses  may 
need  changing  in  a  year,  but  in  spite  of  this  it  is  not  well  to  insist 
on  a  stronger  glass  at  first. 

In  the  third  esse  (I.  B.  J. )  we  gave  more  than  half  the  indicated 
correction  because  the  patient  was  so  near  to  the  half  century  mark ,  thus 
justifying  a  greater  proportional  increase  in  the  strength  of  the  glasses. 

These  cases  were  all  simple  presbyopia,  all  coming  for  their  first 
glasses,  and  yet  there  were  points  of  difference  in  each,  thus 
emphasizing  the  fact  that  in  optometry  there  are  no  hard  and  fast 
rules  to  be  blindly  followed  even  in  cases  suffering  from  the  same 
form  of  optical  defect. 

We  have  made  a  somewhat  hasty  examination  of  these  cases, 
but  the  history  of  them  led  us  to  believe  that  they  were  simply 


Presbyopia  57 

presbyopic,  and  as  they  were  all  in  the  "forties,"  we  relied  on  a 
subjective  examination  alone,  investigating  only  the  condition  of 
the  accommodation  and  the  refraction.  The  first  being  deficient, 
and  the  second  normal,  the  diagnosis  could  be  none  other  than 
presbyopia. 

But  we  would  earnestly  advise  you  to  go  more  thoroughly  into 
the  examination  of  your  cases.  You  claim  to  be  skilled  opto- 
metrists, and  you  want  to  establish  a  reputation  as  such,  and  there- 
fore in  the  examination  of  all  cases  that  seek  your  services,  you 
should  investigate  every  function  of  the  eyes  and  the  condition  of 
all  their  parts  that  are  accessible  to  your  trained  skill. 

After  determining  the  state  of  the  refraction,  you  should  look 
into  the  muscular  equilibrium  and  thus  detect  any  heterophoria  that 
may  be  present,  either  at  twenty  feet  or  at  reading  distance.  You 
should  use  your  ophthalmoscope  to  determine  the  integrity  of  the 
refracting  media  and  of  the  nerve  head  and  retina.  Also  your  reti- 
noscope  to  verify  the  condition  of  the  refraction. 

In  closing  I  want  to  say  that  presbyopia  is  not  a  well-defined 
departure  form  normal  shape  or  structure  (as  are  the  several  refrac- 
tive errors),  but  rather  an  impairment  of  the  function  of  accommo- 
dation that  comes  on  so  gradually  that  to  a  certain  extent  the  eyes 
adapt  themselves  to  it.  Even  though  the  refraction  is  the  same  in 
two  persons  of  the  same  age,  the  accommodation  is  apt  to  vary, 
and  hence  also  the  measurable  amount  of  presbyopia. 

One  objection  to  stronger  glasses  which  we  have  failed  to  men- 
tion is  that  they  diminish  the  range  of  accommodation  and  tie  the 
patient  down  too  close  to  his  book  or  work.  This  imposes  a  strain 
on  both  the  accommodation  and  the  convergence.  Diminish  the 
strength  of  the  glasses  by  .25  D.  or  .50  D.,  and  you  will  greatly 
extend  the  range  of  accommodation,  and  at  the  same  time  make 
patient  more  comfortable  in  the  use  of  his  eyes. 


Myopia 

[Clinic  No.   io] 

As  a  cursory  glance  through  the  patients  before  us  shows  sev- 
eral cases  of  myopia,  we  will  devote  our  attention  on  this  occasion 
to  the  consideration  of  this  important  refractive  error. 

This  defect  is  one  that  you  do  not  meet  every  day  ;  in  fact, 
the  statement  is  made  that  scarcely  more  than  one  per  cent,  of  all 
eyes  are  affected  with  simple  myopia.  And  yet  on  account  of  its 
tendency  to  progress  and  the  damage  to  ocular  tissues  in  high 
myopia,  it  calls  for  the  greatest  skill  and  judgment  in  its  manage- 
ment. 

J.  M.,  twenty-one  years  of  age.  Cigarmaker  by  occupation. 
The  history  he  gives  us  is  as  follows  :  for  the  past  three  years  he 
has  noticed  that  he  was  short-sighted.  Complains  of  inability  to 
see  across  the  street  and  even  to  recognize  persons  when  passing 
them  on  the  same  side  of  the  street,  except  by  their  voice.  Usually 
no  trouble  in  ordinary  reading,  but  pain  and  lachrymation  when 
reading  music,  more  noticeable  at  night. 

This  history  indicates  a  condition  of  greatly  impaired  vision. 
The  patient  himself  says  he  is  short-sighted,  but  we  must  not  accept 
the  uncorroborated  statement  of  any  patient,  nor  must  we  even 
allow  it  to  influence  our  judgment,  else  we  will  often  be  led  astray. 
Many  a  patient  has  come  to  us  and  told  us  he  was  near-sighted, 
when  an  examination  showed  him  to  be  hypermetropic,  of  such 
high  degree  that  distant  vision  was  impaired  and  the  book  was  held 
close  to  eyes  in  order  to  take  advantage  of  the  larger  visual  angle. 
Therefore  we  must  approach  the  examination  of  a  case  with  unbiased 
judgment  and  proceed  in  accordance  with  our  usual  methods. 

IMPAIRED   VISUAL    ACUITY 

In  trying  to  determine  the  visual  acuteness  in  this  case,  we 
find  that  it  is  very  greatly  impaired.  The  patient  is  scarcely  able  to 
see  the  test  card,  much  less  to  distinguish  any  letters  on  it.  We 
ask  him  to  approach  the  card,  and  it  is  not  until  he  gets  within  four 
or  five  feet  that  he  is  able  to  name  the  largest  letter  at  the  top  of  the 
card.     The  visual  acuity  is,  therefore,  expressed  as  7§7. 


Myopia  59 

When  we  hand  him  the  reading  test  card  you  see  he  at  once 
brings  it  very  close  to  his  eyes,  and  on  measuring  the  distances  we 
find  that  his  near-point  is  three  inches,  and  his  far-point  six  inches, 
which  shows  a  very  limited  range  of  accommodation. 

The  examination  thus  far  has  shown  a  lessened  visual  acuity 
and  a  restricted  far-point,  both  of  which  conditions  are  sympto- 
matic of  myopia,  but  they  are  also  found  in  high  hypermetropia. 
Now,  how  are  we  going  to  decide  which  defect  is  present? 

The  retinoscope  will  determine  this  question  for  us.  The  reflex 
will  be  dull  and  the  movements  slow  in  either  case.  If  hyperme- 
tropia is  present,  the  movement  is  seen  to  be  "with,"  and  convex 
lens  will  brighten  the  reflex  and  make  movement  faster  and  more 
noticeable.  In  myopia  the  movement  is  "against,"  and  a  concave 
lens  is  needed  to  clear  the  reflex  and  the  movement. 

The  ophthalmoscope  might  also  be  used  ;  the  direct  method  is 
preferable,  and  if  hypermetropia  is  present,  the  disk  is  small  and 
the  picture  of  the  fundus  is  improved  by  convex  lenses. 

In  myopia  the  optic  disk  is  large  and  indistinct,  and  a  concave 
lens  is  needed  to  reduce  it  more  to  its  normal  size  and  make  it 
clearer. 

But  doubtless  some  of  the  members  of  the  class  are  not  familiar 
with  these  objective  methods  of  examination,  and  for  their  benefit 
we  will  adhere  to  the  subjective  form  oi  examination  by  means  of 
the  trial  case. 

In  accordance  with  our  rule  we  will  try  convex  lenses  first,  and 
as  the  symptoms  indicate  a  high  degree  of  defect,  it  is  useless  to 
commence  with  such  weak  lenses  as  .  25  D.  or  .  50  D.  We  will  try 
a  +  2  D.  Patient  says  it  makes  vision  decidedly  worse.  You  will 
notice  that  this  young  man  is  not  seated  at  our  usual  distance  of 
twenty  feet,  but  that  I  have  brought  him  closer  and  placed  his  chair 
at  about  six  feet.  In  cases  like  this,  where  the  vision  is  so  greatly 
impaired,  the  retinal  images  produced  by  objects  at  a  distance  ot 
twenty  feet  are  so  much  blurred  that  patient  is  scarcely  able  to 
determine  whether  a  certain  lens  makes  vision  better  or  worse,  and 
hence  the  tests  at  the  usual  distance  are  unsatisfactory. 

When,  however,  the  patient  is  seated  where  we  have  placed 
him,  the  vision  is  sufficiently  good  to  enable  the  top  letter  to  be 
deciphered,  and  hence  the  effect  of  certain  lenses  can  be  much  bet- 
ter determined.  If  the  patient  was  seated  at  the  usual  distance, 
the  vision  is  so  very  much  blurred  that  he  would  scarcely  be  able  to 


6o  Clinics  in  Optometry 

tell  me  whether  the  addition  of  the  convex  lens  made  it  any  worse 
or  not. 

We  have  allowed  this  -f  2D.  lens  to  remain  before  the  eye  for 
a  moment,  because  if  hypermetropia  is  present  it  will  encourage  a 
relaxation  of  the  accommodation  and  vision  gradually  improves  as 
the  eye  adapts  itself  to  the  glass.  But  in  this  case  there  is  no  such 
improvement,  and  hence  we  remove  the  lens  and  replace  it  with  a 
—  2D.  The  change  in  the  expression  of  the  patient's  face  tells  us 
at  once  that  this  lens  is  more  acceptable,  and  in  answer  to  our  ques- 
tion he  says  the  letter  E  is  much  sharper  and  blacker  and  he  can 
almost  determine  the  two  letters  on  the  second  line. 

MYOPIA    INDICATED 

We  have  now  proven  that  the  refraction  of  this  young  man's 
eyes  is  myopic,  and  this  indicates  the  direction  along  which  our 
examination  must  be  made.  We  now  ask  our  patient  to  return  to 
the  chair  at  the  customary  twenty  feet  distance,  and  we  will  see 
what  information  can  be  gained  from  the  pin-hole  disk.  We  ask 
the  patient  to  hold  it  close  in  front  of  each  eye  while  the  other  is 
covered,  and  after  a  little  hesitation  he  names  these  letters  in 
answer  to  our  inquiry  as  to  the  lowest  line  he  can  read,  C  B  L  C  T 
O,  which  you  will  recognize  as  the  No.  30  line,  which  properly 
reads  O  E  L  C  T  G.  This  test  proves  that  the  impaired  vision  is 
due  to  a  refractive  error  and  indicates  the  extent  to  which  it  can  be 
improved,  and  as  our  previous  test  showed  the  refraction  to  be 
myopic,  we  now  have  a  pretty  fair  understanding  of  the  case  and  all 
that  remains  is  to  measure  the  amount  of  the  myopia. 

We  test  each  eye  separately,  gradually  increasing  the  strength 
of  the  concave  lenses  until  we  reach  —  6  D. ,  with  which  V.  =  f  $. 
A  —  6.50  D.  lens  affords  the  same  acuteness  of  vision,  but  makes 
the  letters  smaller.  A  —  .50  D.  cyl.  axis  1800,  placed  in  front  of 
the  —  6  D.  is  accepted  as  an  improvement  and  enables  patient  to 
guess  that  the  first  letter  on  the  No.  20  line  is  an  A,  all  other  letters 
being  blurred  and  illegible. 

Now  that  we  have  measured  the  error  of  refraction,  what 
glasses  shall  we  order  ?  It  would  seem  like  a  simple  matter  to  give 
this  young  man  a  pair  of  —  6  D.  S.  Q  —  .50  D.  cyl.  axis  1800  and 
send  him  on  his  way  rejoicing,  but  I  want  to  say  to  you  that  the 
prescribing  of  glasses  in  myopia  is  a  serious  matter  and  should 
receive  the  most  careful  consideration  from  every  point  of  view. 


Myopia  61 

This  case  may  properly  be  classed  as  one  of  high  myopia,  in 
which  two  pairs  of  glasses  should  be  ordered,  one  pair  for  distant 
vision  and  the  other  pair  for  close  use. 

PRESCRIBING    GLASSES    IN    MYOPIA 

This  young  man  has  never  worn  glasses  and  his  myopia  has 
undoubtedly  been  increasing  from  year  to  year  as  a  result  of  the 
neglect.  On  account  of  the  myopic  condition  of  his  eyes,  by  means 
of  which  they  are  adapted  for  near  vision,  but  little  effort  of  accom- 
modation has  been  required.  As  a  consequence,  his  ciliary  muscle 
is  weak  and  deficient  in  sphincter  fibers,  and,  in  fact,  may  be  con- 
sidered as  somewhat  atrophied.  If  we  should  give  him  a  full  cor- 
rection with  instructions  to  wear  the  glasses  constantly,  both  far  and 
near,  a  heavy  tax  would  be  placed  upon  the  ciliary  muscle,  with 
one  of  two  results  as  follows  :  the  muscle  would  be  forced  into 
unaccustomed  activity,  making  the  patient  very  uncomfortable  and 
with  all  the  symptoms  of  marked  asthenopia.  Or  the  muscle  would 
be  unable  to  respond  to  the  call  upon  it,  and  as  a  consequence  the 
rays  of  light  could  not  be  focused  upon  the  retina  and  vision  would 
be  indistinct,  especially  for  near  objects,  in  fact  reading  would  be 
an  impossibility. 

These  facts  lead  to  the  rule  that  was  long  ago  adopted  to 
govern  the  prescribing  of  glasses  in  myopia,  viz.,  that  they  should 
be  the  weakest  possible  consistent  with  a  fair  visual  acuity,  and  that 
in  the  higher  degrees  even  these  must  be  modified  for  close  vision. 

For  the  reasons  just  mentioned  we  do  not  think  it  advisable  to 
order  glasses  stronger  than  —  5  D.  for  distant  vision,  and  —  3D. 
for  reading  and  work,  omitting  the  cylinder  as  of  no  very  special 
advantage. 

A  myopic  eye  is  really  a  "sick"  eye,  and  the  prescribing  of 
glasses  is  only  a  part  of  the  general  treatment  which  such  eyes 
should  receive.  Without  proper  precautions  glasses  alone  may  do 
more  harm  than  good.  When  myopia  is  once  established,  its  con- 
stant tendency  is  to  increase  not  only  to  the  great  impairment  of 
vision,  but  to  actual  damage  to  the  tissues  of  the  eye.  If  we  had 
seen  this  young  man  ten  years  ago,  when  perhaps  his  myopia  was 
less  than  half  it  is  to-day,  we  feel  sure  we  could  have  checked  the 
progress  of  the  defect  and  sent  him  through  life  with  a  much  better 
pair  of  eyes  than  he  has  to-day.  But  "it's  better  late  than  never," 
and  hence  we  will  give  him  some  advice  in  addition  to  his  glasses. 


62  Clinics  in  Optometry 

BE    CAUTIOUS    IN    USING    THE    GLASSES 

He  should  be  careful  in  reading  and  working  to  have  a  good 
steady  clear  light :  coming,  if  possible,  from  the  left  side  but  never 
from  in  front. 

If  it  is  possible  for  this  young  man  to  do  so,  we  would  advise 
him  to  change  his  occupation  for  one  in  which  he  would  not  be  so 
closely  confined.  If  not,  his  hours  of  work  should  be  restricted  and 
he  should  arrange  for  a  great  deal  of  out-door  exercise.  After 
working  all  day,  he  should  do  no  reading  at  night  or  very  little. 

While  at  work  at  his  bench  he  should  sit  erect  and  incline  his 
head  as  little  as  possible,  as  otherwise  a  congestion  of  the  ocular 
tissues  is  favored,  which  is  a  cause  of  the  origin  and  continuance  of 
a  myopia.  This  keeps  his  work  at  a  proper  distance  from  his  eyes, 
and  the  same  precaution  should  be  observed  in  reading  and  writing. 

We  would  advise  him  to  abandon  his  music  to  a  great  extent, 
and  in  what  little  reading  he  does  to  select  clear  print  of  good  size. 

Persons  engaged  in  sedentary  occupations  as  he  is  (cigar- 
making,  you  will  remember),  are  apt  to  be  of  a  constipated  habit. 
He  should  endeavor  to  correct  this  tendency  and  pay  every  atten- 
tion to  the  condition  of  his  health. 

As  I  have  laid  so  much  stress  on  the  seriousness  of  myopia  and 
the  necessity  for  care  in  the  use  of  the  eyes  and  skill  in  the  adjust- 
ment of  glasses,  it  may  be  well  to  say  a  word  as  to  the  causes  that 
produce  this  condition. 

DEFINITION    OF    MYOPIA 

Myopia,  as  you  all  know  from  your  previous  studies,  is  that 
condition  of  refraction  in  which  the  rays  of  light  come  to  a  focus  in 
front  of  the  retina.  This  may  be  caused  by  an  increase  of  refract- 
ing power  of  some  of  the  media,  as  a  shortening  of  the  radius  of 
curvature  of  the  cornea  or  an  increase  in  the  convexity  of  the 
crystalline  lens,  the  latter  being  pioduced  by  spasm  of  the  accom- 
modation, at  first  only  temporarily,  but  which  later  develops  into  a 
permanent  condition. 

However,  our  usual  understanding  of  a  myopic  eye  is  one  in 
which  there  is  an  elongation  of  the  ball  itself  in  the  antero-posterior 
direction. 

While  heredity  is  looked  upon  as  a  predisposing  cause,  you 
must  not  think  that  the  babe  is  born  necessarily  with  myopic  or 
elongated  eyes.      Only  the  predisposition  to  myopia  is  inherited, 


Myopia  63 

which  means  that  the  coats  of  the  eye  are  weak  and  elongate  from 
an  amount  of  overuse  or  strain  that  would  have  no  effect  upon  the 
normal  eye. 

In  this  connection  we  wish  to  impress  upon  you  the  import- 
ance of  being  on  your  guard  not  to  mistake  a  case  of  false  myopia 
(which  is  really  hypermetropia  over-corrected  by  spasm  of  the 
accommodation)  for  real  myopia,  and  we  hope  none  of  you  will  ever 
be  guilty  of  putting  concave  lenses  on  hypermetropic  eyes.  This  is 
an  error  that  can  be  easily  made,  and  in  our  experience  we  have 
seen  many  examples  of  it. 

HYPERMETROPIA    SIMULATING    MYOPIA 

The  hypermetropic  child  simulates  myopia,  because  he  holds 
his  book  very  close.  He  does  this  in  order  to  obtain  a  larger  reti- 
nal image  ;  the  image  is  not  clear  because  it  is  composed  mostly  of 
diffusion  circles,  but  what  it  lacks  in  clearness  it  makes  up  in  size. 

When  such  a  child  is  brought  to  the  optometrist,  the  state- 
ment is  usually  made  by  the  parents  or  by  the  child  himself  that  he 
is  near-sighted.  Such  statement  is  made  in  all  innocence,  because 
of  the  near  position  of  the  book.  But  if  you  accept  such  statement 
as  indicating  myopia,  which  has  often  been  done,  you  are  making 
the  first  step  in  the  path  of  grievous  erron  And  if  you  are  led  to 
regard  the  case  as  one  of  myopia,  what  is  more  natural  than 
that  you  should  commence  your  test  with  concave  lenses  ;  this 
means  a  great  many  steps  in  the  same  path  of  error,  because  such 
concave  lenses  will  be  accepted  by  the  patient  and  then  prescribed 
by  you.  They  are  accepted  because  the  diminishing  effect  of  the 
concave  lenses  serves  to  neutralize  the  excessive  refraction  caused 
by  the  spasm  of  accommodation.  But  the  wearing  of  such  concave 
lenses  spurs  the  ciliary  muscle  to  still  greater  contraction,  with 
accompanying  symptoms  of  asthenopia,  which  will  soon  transform 
this  case  of  simulated  into  real  myopia,  and  all  because  you 
were  too  lazy  to  make  the  proper  examination  yourself  or  too 
ignorant  to  know  how  to  do  it,  but  were  satisfied  to  accept  the 
patient's  diagnosis  without  a  question. 

If  now,  on  the  other  hand,  you  ascertain  for  yourself  by  the 
various  tests  with  which  you  are  all  familiar,  that  the  refraction  is 
really  hypermetropic  and  you  prescribe  the  proper  convex  lenses, 
the  after  history  of  the  case  will  be  entirely  different.  The  convex 
lenses  will  relieve  the  strain  on  the  accommodation,  will  form  clear 


64  Clinics  in  Optometry 

and  well-defined  images  on  the  retina  in  place  of  diffusion  circles, 
the  necessity  for  holding  the  book  close  will  be  removed,  and  the 
eyes  will  be  no  longer  directed  myopic-ward,  but  will  rather  be 
turned  towards  emmetropia. 

A    WORD    OF    CAUTION 

Therefore,  when  a  child  is  brought  to  you  with  a  history  of 
near-sightedness,  based  on  holding  the  book  close,  do  not  fall  into 
any  such  trap  as  I  have  mentioned.  Remember  that  very  few 
children  have  myopia,  that  the  prevailing  error  of  refraction  in 
childhood  is  hypermetropia.  Therefore,  in  any  child,  no  matter 
what  the  symptoms,  always  suspect  hypermetropia,  and  make  your 
examinations  with  this  thought  constantly  in  your  mind. 

I  feel  that  I  cannot  too  strongly  emphasize  the  importance  of 
this  matter.  The  examination  of  a  child's  eyes,  when  the  tissues 
are  soft  and  yielding  and  liable  to  give  way  under  strain,  imposes 
upon  us  a  much  greater  responsibility  than  in  the  case  of  an  adult 
where  the  coats  of  an  eye  are  firm  and  unyielding  and  able  to  resist 
the  tendency  to  elongation. 

It  is  unnecessary  to  add  that  at  all  times  the  cases  of  children 
should  be  given  the  most  scrupulous  care  by  the  refractionist.  The 
child's  life  and  preparation  therefor  are  still  before  it,  and  its  future 
may,  to  some  extent,  be  influenced  for  good  or  the  reverse  by 
proper  or  improper  treatment  of  its  eye  defect  at  the  hands  of  the 
optician. 


Monocular  Vision 


[Clinic  No.   ii] 

Among  the  patients  who  have  applied  to  us  for  treatment 
recently  were  three  whose  visual  defect  was  monocular  vision,  and 
the  thought  occurred  to  us  that  it  would  not  be  unprofitable  to 
bring  them  together  and  present  them  as  the  subject  of  this  clinic. 

Miss  E.  V.  H.  is  thirty-five  years  of  age.  She  tells  us  she  had 
convergent  strabismus  in  youth,  at  which  time  a  tenotomy  was  per- 
formed. She  claims  now  that  her  eyes  ache  continuously  and  have 
been  doing  so  for  the  past  six  months. 

As  we  look  at  this  lady's  eyes  we  notice  at  once  that  there  is 
still  a  condition  of  convergent  strabismus,  the  right  eye  being  the 
deviating  eye. 

An  examination  of  the  acuteness  of  vision  results  as  follows  : 

R.  E. ,  unable  to  see  any  letters  on  the  test  card. 

L.  E. ,  f-£  ?  ?  ?.  You  will  notice  that  she  reads  the  No.  20 
line,  but  that  she  mistakes  three  of  the  letters  on  the  line. 

We  now  proceed  to  make  a  more  careful  examination.  We 
cover  the  left  eye  and  lead  the  patient  toward  the  card  asking  her 
every  step  or  two  she  makes  whether  she  is  able  to  see  any  letters 
on  the  card.  It  is  not  until  she  gets  within  five  feet  of  the  card  that 
she  is  able  to  distinguish  the  largest  letter,  and  we  have,  therefore, 
made  a  record  of  the  acuteness  of  vision  as  -^n- 

THE    PIN-HOLE    TEST 

You  will,  perhaps,  recall  our  method  of  precedure  in  cases  of 
extremely  defective  vision,  which  we  have  so  often  described,  and 
that  is  to  determine  the  possibility  of  improvement  in  vision  by 
means  of  the  pin-hole  disk.  If  the  pin-hole  improves  vision,  we 
can  expect  an  equal  (and  sometimes  a  greater)  improvement  by 
means  of  the  lenses.  While,  on  the  other  hand,  if  the  pin-hole  fails 
to  afford  an  improvement,  you  will  know  the  case  is  hopeless  and 
no  benefit  is  to  be  expected  from  glasses. 

We  will,  therefore,  take  the  pin-hole  disk  from  the  trial  case, 
and  still  keeping  the  left  eye  covered,  direct  the  patient  to  hold  the 
disk  close  in  front  of  the  sight  of  the  right  eye.     The  sight  is  so 


66  Clinics  in  Optometry 

greatly  impaired  that  patient  finds  considerable  difficulty  in  getting 
the  disk  in  proper  position.  At  first  she  says  everything  is  black 
because  she  is  trying  to  look  through  the  opaque  part  of  the  disk. 
But  finally,  after  several  trials,  she  succeeds  in  placing  it  in  the  line 
of  vision,  but  the  result  is  nil.  We  have  allowed  the  patient  to 
remain  at  the  distance  at  which  she  could  first  see  the  large  letter, 
but  there  is  so  much  loss  of  illumination  and  so  few  rays  of  light 
enter  the  eye,  that  even  the  large  letter  at  the  top  of  the  card  now 
is  scarcely  legible.  This  proves  that  the  impaired  vision  is  not  due 
to  an  error  of  refraction  and  that  no  improvement  is  to  be  expected 
from  lenses.  We  will  now  make  an  ophthalmoscopic  examination. 
We  find  that  all  the  media  are  clear  and  that  there  are  no  marked 
changes  at  fundus  of  the  eye.  The  retina  and  optic  disk  are  paler 
than  normal  and  the  details  are  but  dimly  seen.  We  diagnose  the 
condition  as  amblyopia. 

Now  a  word  in  passing  as  to  the  cause  of  this  amblyopic  condi- 
tion of  the  retina.  It  is  undoubtedly  due  to  non-use  and  is  present 
to  a  greater  or  less  extent  in  nearly  every  case  of  strabismus.  I  can 
assure  you,  however,  that  it  is  a  preventable  condition,  but  is 
allowed  to  become  amblyopic  from  neglect,  from  failure  to  consult 
a  specialist  who  could  have  pointed  out  the  dangers  and  indicated 
the  proper  methods  to  be  pursued  to  preserve  vision. 

PROBABLE    HISTORY    OF    THE    CASE 

It  is  more  than  likely  that  this  lady  started  life  with  an  equal 
amount  of  vision  in  each  eye.  That  her  eyes  were  hypermetropic. 
That  at  the  age  of  three  or  four  (or  perhaps  a  year  or  two  later)  a 
convergent  strabismus  began  to  develop.  That  this  excessive 
convergence  was  caused  by  the  extra  accommodation  required 
to  overcome  hypermetropia  when  she  first  commenced  to  use 
her  eyes  for  near  vision.  That  the  tenotomy  was  probably  not 
performed  early  enough  and  that  it  failed  to  restore  binocular 
vision. 

We  said  that  this  amblyopia  was  preventable.  When  this 
operation  was  performed  in  youth,  the  vision  of  each  eye  should 
have  been  carefully  examined.  If  that  of  the  right  eye  was  found 
deficient,  a  special  effort  should  have  been  made  to  improve  it. 
This  can  be  accomplished  by  covering  the  good  eye  and  compelling 
the  defective  eye  to  perform  the  act  of  vision,  and  continuing  this 
procedure  until  the  vision  of  the  two  eyes  is  nearly  or  quite  equal- 


Monocular  Vision  67 

ized.      Then   binocular  vision  can    be    cultivated,   perhaps    by  the 
assistance  of  prisms. 

In  the  consideration  of  cases  of  this  kind,  there  are  two  things 
of  which  you  may  be  assured  : 

1.  That  when  an  eye  fails  to  participate  in  the  act  of  vision,  as 
in  the  deviating  eye  in  strabismus,  it  loses  its  sharpness  of  sight  and 
becomes  amblyopic. 

2.  That  if  such  an  eye  is  compelled  to  perform  its  function, 
under  persistent  and  intelligent  direction,  the  sight  can  be  very 
greatly  improved  and  in  the  majority  of  cases  restored  to  normal. 
We  have  been  able  to  accomplish  this  result  in  our  work  here  in  a 
great  many  cases,  the  most  favorable  for  improvement,  of  course, 
being  those  who  are  young  and  where  the  amblyopia  is  not  of  long 
standing.  But  the  older  cases  are  not,  by  any  means,  hopeless,  as 
has  been  proven  several  times  to  my  knowledge,  where  an  accident 
in  adult  life  has  destroyed  the  sight  of  the  good  eye,  the  amblyopic 
eye  which  was  formerly  useless  now  begins  to  assume  the  work  of 
vision  and  soon  develops  into  a  useful  organ.  But  prevention  is 
better  than  cure  always,  and  therefore  I  would  impress  upon  you 
the  importance  of  recognizing  these  cases  in  early  childhood  in 
order  that  you  may  be  in  position  to  give  the  proper  advise  to  pre- 
vent a  failure  of  vision  which  is  otherwise  inevitable. 

In  this  case  the  right  eye  is  practically  useless  as  an  organ  of 
vision.  We  call  this  condition  monocular  vision,  which  literally  means 
one-eye  vision.  The  time  for  making  an  effort  to  improve  vision 
has  long  since  passed,  because  it  would  require  more  time,  patience 
and  perseverance  than  a  patient  is  able  or  willing  to  give  to  it. 
Therefore,  in  this  case,  our  efforts  must  be  directed  to  preserving 
and  conserving  the  sight  of  the  other  eye. 

We  find  the  acuteness  of  vision  of  this  eye  \%  partly.  Before 
commencing  the  test  with  trial  lenses,  we  will  ask  to  see  the  glasses 
patient  has  been  wearing,  and  on  neutralizing  them  find  that  the  left 
lens  is  -(-  .75  D. ,  but  which  patient  says  is  unsatisfactory. 

We  place  a  +  .  50  D.  sphere  in  the  trial  frame.  Patient  says 
this  makes  no  difference,  vision  is  just  the  same  with  it  as  without 
it.  We  substitute  a  -f  .50  cylinder,  which  we  place  with  axis  at 
900.  This  we  are  told  is  no  better,  but  before  removing  it,  as  is 
our  usual  custom,  we  will  rotate  it.  As  the  axis  turns  toward 
patient's  left,  she  says  it  makes  vision  notably  worse.  We  now  rotate 
in  the  opposite  direction  and  patient  tells  us  this  begins  to  improve 


68  Clinics  in  Optometry 

vision.  After  a  few  trials  we  find  that  the  proper  position  for  the 
axis  is  at  1350,  when  vision  is  at  its  best  and  the  No.  20  line  is 
quite  legible. 

WHAT    CONVERGENT    STRABISMUS    INDICATES 

The  presence  of  the  convergent  strabismus  leads  us  to  believe 
that  there  is  more  of  a  hypermetropic  element  in  the  case  than  is 
indicated  by  the  convex  cylinder  that  has  just  been  accepted.  In 
order  to  prove  or  disprove  this  supposition,  we  place  convex 
spheres  in  the  trial  frame  in  connection  with  the  cylinder.  We 
commence  with  -f-  .50,  with  which  patient  says  vision  is  the  same  ; 
-j-  .75  and  -\-  1  are  accepted  in  turn,  but  when  -j-  1.25  is  placed 
before  the  eye,  she  says  she  cannot  see  the  letters  so  well.  We 
therefore  replace  it  with  the  -f  1,  which  in  combination  with  the 
cylinder  affords  a  vision  f#,  clearly  and  comfortably.  This  com- 
pound lens  then  represents  the  manifest  error  of  refraction,  which  is 
a  compound  hypermetropic  astigmatism. 

We  have  worked  out  the  correction  in  this  case  pretty  care- 
fully, and  there  is  scarcely  any  doubt  that  the  formula  mentioned 
would  be  the  proper  one  to  prescribe.  Doubtless  many  of  you 
think  we  have  already  spent  too  much  time  in  the  examination  of 
this  case,  and  would  feel  satisfied  to  dismiss  it  without  any  further 
investigation.  But  we  hope  there  are  some  among  you  who  feel 
that  an  educated  optometrist  should  not  rest  content  with  a  simple  test 
case  examination  and  correction.  And  this  is  the  sentiment  I  want 
to  encourage,  in  the  hope  that  it  will  spread  until  all  of  you  are  of 
the  same  mind.  There  is  no  question  that  the  man  who  is  confined 
to  one  method  of  examination  and  knows  no  other,  is  not  entitled 
to  a  front  seat  in  the  profession  of  optometry,  nor  will  he  be  able  to 
hold  his  own  when  he  comes  in  competition  with  more  versatile 
refractionists. 

FOGGING    AND    RETINOSCOPE    TESTS 

Therefore,  we  will  employ  two  other  methods  of  examination, 
in  order  to  determine  if  the  result  obtained  from  the  first  method  is 
correct. 

First,  the  fogging  method.  We  place  a  -f-  5  D.  lens  in  the 
trial  frame,  which  of  course,  greatly  fogs  the  vision.  We  reduce 
with  concaves  until  we  have  +  2.25  value  in  front  of  the  eye  with 
which  the  No.  20  line  is  partly  legible.  We  then  direct  patient's 
attention  to  the  card  of  radiating  lines,  and  in  answer  to  our  ques- 


Monocular  Vision  69 

tion  as  to  the  difference  in  their  distinctness,  she  says  the  lines  from 
300  to  6o°  are  dull  as  compared  with  the  others.  With  this  as  a 
clue,  we  place  a  —  .50  cylinder  with  its  axis  oblique  in  front  of  the 
convex  sphere.  This  at  once  clears  up  the  lines,  and  on  directing 
her  attention  to  the  letters,  we  find  that  the  No.  20  line  has  been 
made  much  clearer  by  the  addition  of  the  cylinder.  By  transposing 
this  formula,  the  result  of  the  fogging  test  is  +  1.75  S.  C  +  -5° 
cyl.  axis  1350. 

We  will  now  measure  the  refraction  by  the  retinoscope.  As 
we  cause  the  shadow  to  move  across  the  naked  pupil,  we  see  at 
once  the  movement  is  "with."  We  place  a  -f-  1  D.  in  the  trial 
frame  and  the  movement  is  still  with  ;  we  replace  this  lens  with  a 
-}-  2  D. ,  with  the  same  result.  We  increase  to  -f-  2.50  D.  with 
which  the  movement  is  neutralized  in  some  of  the  meridians.  On 
careful  observation  we  find  that  the  meridian  in  which  there  is  the 
11105*1  decided  ' '  with ' '  movement  remaining,  is  the  45th.  This 
calls  for  a  further  increase  in  this  meridian,  and  we  find  that  a  -f-  3 
D.  ' '  kills  ' '  the  movement.  Now,  what  has  the  retinoscope  given 
us  ?  Perhaps  we  can  make  the  retinoscope  findings  clearer  to  you 
by  a  diagram  on  the  blackboard  : 


135 


+  3D-  +2.50D. 

After  making  allowance  for  the  one  meter  at  which  test  is 
made,  the  result  is  as  follows  :  The  refraction  of  the  45th  meridian 
is  -f  2D.,  and  of  the  135th,  +  1.50  D.,  which  would  call  for  the 
following  correction  :  -f-  1.50  D.  Q  +  .50  D-  cyl.  axis  1350. 

A  comparison  of  the  results  obtained  by  these  three  methods, 
although  at  first  sight  apparently  disagreeing,  really  shows  no  dis- 
crepancy. 


70  Clinics  in  Optometry 

The  test  case  measures  the  manifest  error,  while  the  retino- 
scope  and  the  fogging  method  bring  out  the  latent  error,  the 
latter,  in  this  case,  developing  more  of  the  latent  defect  than 
does  the  retinoscope. 

ANOTHER    ILLUSTRATIVE    CASE 

Mrs.  S.  W.  K.,  aged  sixty-seven  years.  We  have  been 
unable  to  get  much  of  a  history  from  this  old  lady.  All  she  has  to 
say  is,  that  she  thinks  her  glasses  need  changing. 

R.  E. ,  vision  =  f£.    With  -f  2  S.  C  +  .50  cyl.  axis  900  =  \%. 

L.  E.  No  letters  can  be  seen  on  the  test  card.  The  use  of 
the  pin-hole  disk  gives  a  negative  result,  and,  therefore,  it  is  use- 
less to  waste  our  time  in  trying  lenses.  For  reading  we  find  that 
-f-  5. 50  affords  the  best  vision. 

An  examination  of  her  old  glasses  shows  them  to  be  +  2  D. , 
for  distance,  and  -f-  5  for  reading,  and  we  are,  therefore,  justified 
in  changing  them  to  correspond  to  our  examination.  Our  special 
interest  in  this  case,  at  this  time,  lies  in  the  fact  that  it  is  one  of  this 
series  of  monocular  vision. 

H.  R.,  aged  twenty  years.  Telegraph  operator.  Left  eye 
diverges,  twitches  and  waters. 

R.  E.,  vision  =  f#  ?  ?.     With  -f  2  cyl.  axis  no0  Q  +  .50 

c    20 

*■>•  —   2H- 

L.  E. ,  vision  reduced  to  counting  fingers.  Pin-hole  disk  gives 
a  negative  result.  The  ophthalmoscope  shows  an  atrophy  of  the 
retina,  which  is  very  white  and  with  but  few  blood  vessels  and  these 
like  small  threads. 

This  little  series  of  cases  all  present  the  one  feature  of  mono- 
cular vision.  In  two  of  the  cases  the  contributing  cause  is  a  stra- 
bismus ;  in  one  case  convergent,  in  the  other  case  divergent.  In 
the  other  case  there  is  no  deviation  of  the  visual  axis,  and  hence  the 
cause  of  the  loss  of  vision  is  in  doubt. 

In  all  these  cases  the  one  eye  is  beyond  our  help,  and  our  duty 
is  confined  to  a  careful  correction  of  the  other  eye,  in  order  to 
relieve  it  from  undue  strain  and  preserve  it  in  as  good  condition  as 
possible.  While  the  loss  of  the  sight  of  an  eye  may  be  considered 
quite  a  serious  matter,  yet  none  of  these  patients  seem  to  be  incon- 
venienced by  the  sight  being  confined  to  one  eye,  because  they  have 
been  so  long  accustomed  to  monocular  vision  that  it  has  become  a 
second  nature  to  them. 


Mixed  Astigmatism 


[Clinic  No.  12] 

This  young  man  (H.  L.  P.)  is  twenty-two  years  of  age,  and 
has  just  graduated  as  a  civil  engineer.  He  complains  of  drowsiness 
after  reading,  and  feels  that  he  can  continue  only  by  forcing  himself 
to  do  so.  You  see  he  is  already  wearing  glasses,  which  he  tells  us 
he  has  had  for  six  years.  I  will  ask  one  of  you  to  neutralize  these 
lenses  and  tell  us  what  they  are. 

THE    NEUTRALIZATION   OF    LENSES 

In  the  meantime,  it  will  not  be  out  of  place  to  give  you  a  few 
points  on  the  neutralization  of  lenses.  In  the  first  place,  you 
should  ascertain  whether  the  lens  is  convex  or  concave.  This  is 
determined  by  the  apparent  motion  of  objects  seen  through  the  lens. 
If  the  motion  is  opposite,  the  lens  is  convex  ;  if  in  the  same  direc- 
tion, the  lens  is  concave. 

The  next  point  to  be  determined  is  whether  the  lens  is  a 
sphere,  a  cylinder  or  a  combination  of  both.  For  this  purpose  the 
lens  is  rotated  while  we  look  through  it  at  a  straight  line,  as  for 
instance  the  edge  of  the  window  sash  or  of  a  picture  frame.  If  this 
edge  breaks  as  the  lens  is  turned,  there  is  a  cylindrical  element  in 
it.  If  there  is  no  break,  it  is  a  simple  sphere.  In  the  first  case, 
we  must  next  determine  whether  the  cylinder  is  piano  or  com- 
pound ;  if  we  can  move  the  lens  in  any  one  direction  without  caus- 
ing movement  of  the  object  looked  at,  it  is  a  piano-cylinder  ;  but  if 
there  is  movement  in  every  meridian,  in  some  meridians  more 
marked  than  others,  it  is  a  sphero-cylinder. 

Our  young  friend  is  now  ready  to  report  on  this  lens,  and  he 
tells  us  it  is  a  —  2  D.  cylinder  with  the  axis  at  1800.  Now  let  us 
look  at  the  lens  and  see  how  he  arrived  at  this  conclusion.  As  we 
hold  the  lens  about  ten  inches  in  front  of  our  eye  and  look  through 
it  at  the  window  sash  while  we  rotate  it,  we  see  a  movement  of  that 
part  of  the  sash  seen  through  the  lens,  showing  that  it  is  a  cylinder. 
As  we  move  the  lens  from  side  to  side  there  is  no  motion  ;  as  we 
move  it  up  and  down,  there  is  a  decided  "with"  movement,  thus 
showing  that  it  is  a  piano-cylinder  and  that  it  is  concave. 


72  Clinics  in  Optometry 

In  order  to  neutralize  it  we  take  a  convex  cylinder  from  the 
trial  case,  selecting  -j-  1.50D.,  and  placing  over  the  lens  with  its 
axis  horizontal,  move  it  sideways,  no  motion  ;  move  it  up  and 
down,  still  a  with  movement.  This  convex  cylinder  is  therefore 
not  strong  enough  to  neutralize  the  concave.  We  try  a  +  2.50  D. 
cylinder  in  the  same  position,  and  now  the  up-and-down  movement 
is  opposite,  showing  this  lens  to  be  too  strong.  We  now  select  a 
+  2 .  D.  cylinder,  and  placing  over  the  lens  with  the  axis  horizontal, 
we  find  there  is  perfect  neutralization,  no  movement  in  any  direc- 
tion, and  as  this  is  accomplished  by  a  -f-  2  D.  cylinder  axis  1800, 
we  know  that  the  value  of  the  lens  is  —  2D.  cylinder  axis  1800. 

EXAMINATION    OF    THE    PATIENT 

We  will  now  proceed  to  the  examination  of  our  patient,  and 
we  find  the  acuteness  of  vision  in  each  eye  is  f  %,  while  the  range  of 
accommodation  with  .  50  D.  type  is  from  4"  to  28". 

Bearing  in  mind  the  fact  which  I  have  so  often  tried  to  impress 
upon  your  minds  that  hypermetropic  astigmatism  is  likely  to  be 
mistaken  for  myopic,  we  will  not  allow  ourselves  to  be  misled  by 
the  fact  that  patient  has  been  wearing  concave  cylinders,  but  we  will 
follow  our  invariable  rule  of  trying  convexes  first. 

A  -f-  .  50  D.  sphere  is  positively  rejected.  We  now  try  a  -'- 
.50  D.  cylinder,  which  in  accordance  with  the  usual  custom,  is 
placed  axis  at  900.  This  is  accepted  as  affording  an  improvement 
in  vision,  -f-  .75  D.  cylinder  and  -f  1  D.  cylinder  are  each  accepted 
as  better  than  the  previous  ones,  but  -f-  1.25  D.  cylinder  is  rejected. 
We  rotate  the  cylinder  first  to  the  right,  then  to  the  left,  in  each 
case  blurring  the  letters,  so  that  we  conclude  that  the  proper  posi- 
tion for  the  axis  of  this  1  D.  cylinder  is  at  900,  which  indicates  a 
hypermetropia  of  1  D.  in  the  horizontal  meridian. 

Now  while  this  convex  cylinder  has  afforded  a  marked  improve- 
ment in  vision,  it  has  failed  to  raise  it  to  normal,  and,  therefore,  we 
will  try  the  effect  of  a  concave  cylinder,  commencing  with  —  .50, 
which  as  a  matter  of  course  we  place  with  axis  at  1800.  This  at 
once  sharpens  and  blackens  the  letters,  and  we  keep  on  increasing 
the  concave  cylinders  until  we  reach  —  2D.,  when  we  find  the 
acuteness  of  vision  is  full  f  $.  This  lens  represents  a  myopia  of  2 
D.  in  the  vertical  meridian. 

By  this  simple  method  of  testing,  we  have  arrived  at  the  con- 
clusion that  this  case  is  one  of  mixed  astigmatism. 


Mixed  Astigmatism  73 

SOURCE    OF    ERROR    TO    BEWARE    OF 

The  optometrist  who  fitted  his  present  glasses  entirely  over- 
looked his  hypermetropic  meridian,  and  corrected  only  his  myopic 
meridian.  If  we  had  commenced  our  test  with  concave  cylinders, 
they  would  have  been  accepted  and  would  probably  have  raised 
vision  to  normal,  and  we  would  have  fallen  into  the  same  error  as 
the  previous  fitter.  This  only  serves  to  emphasize  the  importance 
in  our  test  case  examinations  of  commencing  with  convexes,  and 
endeavoring  to  have  them  accepted,  even  though  the  patient  is  at 
first  inclined  to  say  they  are  "  no  better." 

Mixed  astigmatism  is  not  so  uncommon  as  it  might  seem  to  be. 
The  statement  is  made  that  six  persons  out  of  every  hundred  are 
affected  with  this  form  of  error  of  refraction.  It  is  a  combination  of 
simple  hypermetropic  astigmatism  with  simple  myopic  astigmatism, 
with  the  axis  of  the  correcting  cylinders  exactly  at  right  angles  to 
each  other. 

The  correction  as  we  found  it  in  this  case  is  +  1  D.  cylinder 
axis  900  O  —  2D.  cylinder  axis  1800.  This  you  will  recognize  as 
a  case  of  astigmatism  ' '  with  the  rule  ' '  the  vertical  or  myopic  meri- 
dian focuses  parallel  rays  in  front  of  the  retina,  while  the  focus  for 
parallel  rays  of  the  horizontal  or  hypermetropic  meridian  is  behind 

the  retina. 

—  2D. 


-fiD. 


This  little  diagram  which  I  have  placed  on  the  blackboard  will 
serve  to  fix  in  your  minds  the  refraction  of  the  two  principal  meri- 
dians, which  corresponds  to  the  correcting  cross  cylinder,  which  we 
also  place  on  the  blackboard. 

This  cross  cylinder  may  be  transposed  to  a  sphero-cylinder  in 
accordance  with  the  following  rule  : 

Take  either  one  of  the  cylinders  for  the  sphere,  and  the  sum  of 
the  two  for  the  cylinder,  retaining  the  sign  and  axis  of  the  latter. 


74  Clinics  in  Optometry 

This  results  as  follows  :  -f-  I  D.  S.  Q  —  3D.  cylinder  axis 
1800,  —  2  D.  S.  O  +  3  D.  cylinder  axis  900. 

In  order  to  verify  these  transpositions,  let  us  compare  them  with 
the  diagram  on  the  board. 

-f  1  D.  sphere  gives  +  1  value  in  both  vertical  and  horizontal 
meridians.  This  is  what  is  desired  in  the  horizontal  meridian. 
When  we  combine  a  —  3D-  cylinder  axis  1800,  this  horizontal 
meridian  is  unchanged  because  the  axis  of  the  cylinder  has  no 
refractive  value,  while  the  —  3D.  against  the  -4-  1  D.  in  the  verti- 
cal meridian  leaves  —  2D.  value  in  that  meridian,  which  is  just 
what  is  desired. 

In  the  second  sphero-cylinder,  the  —  2D.  sphere  gives  —  2 
value  in  both  meridians.  This  is  correct  for  the  vertical  meridian. 
When  we  combine  with  it  a  -f-  3  D.  cylinder  axis  900,  we  leave 
this  vertical  meridian  undisturbed,  while  the  +  3  D.  against  the  — 
2  D.  in  the  horizontal  meridian  gives  +  1  D.  value  in  this  meri- 
dian, which  is  the  power  desired. 

FOGGING    METHOD    OF    EXAMINATION 

In  any  case  of  refractive  error,  and  especially  in  astigmatism, 
it  is  not  well  to  depend  upon  a  single  method  of  examination,  and, 
therefore,  we  will  proceed  to  the  fogging  method.  It  has  received 
this  name  because  it  makes  vision  indistinct  or  "foggy."  It  is 
intended  to  simulate  cycloplegia,  by  removing  all  need  for  action  of 
the  accommodation  and  placing  it  as  nearly  as  possible  at  rest,  by 
having  in  front  of  the  eye  under  examination  a  convex  sphere  of 
such  strength  as  to  more  than  overcome  any  effort  of  accommoda- 
tion the  eye  might  otherwise  have  to  make  while  looking  at  the 
letters  twenty  feet  away.  The  addition  of  this  strong  convex  lens 
makes  the  eye  to  all  intents  and  purposes,  for  the  time  being  at 
least,  artifically  myopic,  and  we  are  then  in  position  to  proceed  to 
estimate  the  amount  of  error  as  in  any  case  of  regular  myopic 
refraction.  You  will  understand  from  what  I  have  said  that  this 
method  is  only  of  value  in  those  cases  where  a  hypermetropic  ele- 
ment is  suspected,  and  would  not  be  of  service  where  the  eyes  are 
naturally  myopic. 

We  place  a  -)-  4  D.  sphere  in  the  trial  frame  and  ask  the 
patient  to  look  at  the  card  of  radiating  lines.  In  this  case,  as  we 
have  reason  to  believe  that  the  two  principal  meridians  are  vertical 
and  horizontal,  we  will  use  the  card  only  on  which  there  are  verti- 


Mixed  Astigmatism  75 

cal  and  horizontal  lines.  The  patient  says  they  all  looked  blurred,  but 
when  we  question  him  more  closely  he  says  the  vertical  are  darker 
than  the  horizontal.  From  which,  of  course,  we  infer  that  the  hori- 
zontal lines  are  least  distinct. 

Now  our  plan  is  to  add  concave  cylinders  until  we  make  all  the 
lines  equally  distinct  and  black.  You  will  recall  that  the  rule  for 
placing  the  axis  of  the  cylinder  is  in  the  same  direction  as  the  indis- 
tinct lines.  We  place  a  —  1  D.  cylinder  axis  1800  in  front  of  the 
strong  convex  sphere,  and  the  patient  tells  us  that  the  horizontal 
lines  are  now  a  little  darker,  but  not  yet  equal  to  the  vertical  lines. 
We  increase  this  cylinder  .  50  D.  at  a  time,  and  when  we  reach  — 
3  D. ,  the  vertical  and  horizontal  lines  look  both  alike. 

A    CASE    OF    SIMPLE    MYOPIA 

This  cylinder  represents  the  amount  of  astigmatism,  and  the 
case  is  now  reduced  to  one  of  simple  myopia,  which  we  must  cor- 
rect by  the  addition  of  concave  spheres. 

We  now  remove  the  card  of  radiating  lines  and  replace  it  with 
the  card  of  test  letters.  You  will  remember  there  is  in  the  trial 
frame  the  original  +  4  D.  sphere  and  a  —  3D.  cylinder  with  axis 
at  1800.  Patient  says  he  can  scarcely  make  out  the  E  at  the  top  of 
card,  which  is  the  200  feet  letter.  We  add  a  —  .50  D.  sphere 
which  affords  a  slight  improvement,  and  we  keep  on  increasing  the 
concave  sphere,  each  change  causing  a  further  improvement  until 
we  reach  —  3D.  sphere,  when  the  vision  equals  f-$. 

Now  let  us  see  what  we  have  in  the  trial  frame.  I  will  write  it 
on  the  blackboard  so  that  all  of  you  can  follow  me. 

+  4  D.  S.  C  —  3  D.  cyl.  axis  1800. 
-  3  D.  S. 


+  1  D.  S.  C  —  3  D.  cyl.  axis  1800. 

This  formula  you  see  is  identical  with  one  of  the  sphero-cylin- 
drical transpositions  of  the  cross-cylinder,  and  is  equivalent  to  the 
other  sphero-cylinder  and  to  the  cross-cylinder. 

Inasmuch  as  it  is  advisable  for  you  to  use  a  cycloplegic  only  in 
very  exceptional  cases,  I  would  recommend  the  fogging  method  to 
you  as  the  best  substitute  for  developing  the  latent  error  in  any 
case  of  supposed  hypermetropic  refraction,  whether  simple  or  com- 
pound. After  you  have  had  a  little  experience  with  it,  you  will  often 
be  surprised  how  much  of  the  latent  defect  you  will  be  able  to  uncover. 


76  Clinics  in  Optometry 

THE    STENOPAIC    SLIT 

In  the  further  examination  of  this  case,  we  will  make  use  of  the 
stenopaic  slit.  The  patient  looks  at  the  test  letters  (not  at  the 
radiating  lines  as  some  of  you  might  suppose)  and  we  place  the  slit 
in  the  trial  frame  at  900.  Patient  says  the  letters  are  all  blurred, 
;nd  he  is  unable  to  name  even  the  larger  letters.  We  begin  to  rotate 
the  slit  with  the  effect  of  improving  vision  and  when  we  get  to  the 
horizontal  position,  patient  is  able  to  name  the  letters  on  the  No.  20 
line.  This  proves  that  the  horizontal  meridian  is  the  one  of  best 
vision,  and  it  may  be  either  emmetropic  or  hypermetropic.  This 
point  is  to  be  determined  by  the  acceptance  or  rejection  of  convex 
lenses. 

We  use  convex  spheres  (not  cylinders  as  some  of  you  might 
suppose)  commencing  with  +  .50  D. ,  and  increasing  until  rejected. 
We  find  that  a  +  1  D.  is  accepted,  but  a  -f-  1.25  D.  makes  the  No. 
20  line  markedly  indistinct.  This  proves  then  that  the  horizontal 
meridian  is  hypermetropic  and  to  the  extent  of  1  D. 

We  now  turn  the  slit  around  a  quarter  of  a  circle  to  the  meri- 
dian of  poorest  vision  at  .90°.  According  to  our  custom,  we  will 
commence  to  test  with  convex  spheres.  These  are  unhesitatingly 
rejected.  We  then  try  concaves,  which  are  quickly  accepted.  A 
—  1  D.  brings  the  larger  letters  into  view,  and  we  increase  .  25  D. 
at  a  time  until  we  reach  —  2D.,  with  which  the  No.  20  line  is 
legible.  This  proves  that  the  vertical  meridian  is  myopic  to  the 
extent  of  2  D. 

AXIS    AND    MERIDIAN 

We  now  have  determined  the  location  of  the  two  principal 
meridians  and  the  refraction  of  each,  and  as  there  is  sometimes  a 
confusion  in  the  minds  of  optical  students  as  to  the  correct  meaning 
of  "axis  "  and  "  meridian,"  I  will  make  a  diagram  on  the  board. 

—  2  meridian,   not  axis. 


-  +  1  meridian, 
not  axis. 


Mixed  Astigmatism  77 

Now  you  must  remember  that  these  are  the  defective  meri- 
dians, and  that  the  axis  of  the  correcting  cylinders  must  be  placed 
not  in  these  meridians,  but  at  right  angles  to  them,  because  the 
axis  of  the  lens  is  plane  and  the  refractive  power  of  the  lens  is  at 
right  angles  to  axis. 

The  result  then  of  the  test  by  the  stenopaic  disk  is  -f-  1  D. 
cylinder  axis  900  O  —  -  D.  cylinder  axis  1800,  thus  corroborating 
the  other  tests. 

The  stenopaic  disk  shows  a  difference  of  3  D.  between  the  two 
meridians,  the  refraction  of  the  vertical  meridian  being  2  D.  above 
emmetropia,  and  the  horizontal  meridian  1  D.  less  than  normal. 

A  —  3D.  cylinder  axis  1800  overcorrects  the  vertical  meri- 
dian 1  D. ,  and  leaves  the  horizontal  meridian  unaffected  at  -f-  ! 
D.  Hence  a  -|-  1  D.  sphere  combined  with  this  cylinder  corrects 
the  total  error  of  refraction. 

A  -f-  3  D.  cylinder  axis  900  overcorrects  the  horizontal  meri- 
dian, and  makes  it  myopic  to  the  extent  of  2  D.  ;  and  as  the  verti- 
cal meridian  is  unaffected  by  this  cylinder,  both  meridians  are  now 
equally  myopic  to  the  extent  of  2  D.'  Therefore,  a  —  2D.  sphere 
combined  with  this  convex  cylinder  will  represent  the  total  refrac- 
tive error. 

This  case  of  astigmatism  may  be  classed  as  regular,  mixed, 
symmetric  and  with  the  rule. 

As  so  many  beginners  in  optometry  dread  meeting  a  case  of 
mixed  astigmatism,  I  have  purposely  refrained  from  using  the 
objective  methods,  ophthalmoscope,  retinoscope  and  ophthalmo- 
meter, and  have  demonstrated  to  you  how  such  cases  may  be 
worked  out  by  the  simpler  and  more  common  subjective  methods. 


Anisometropia 


[Clinic  No.  13] 

Mrs.  J.  C,  aged  twenty-eight  years,  complains  principally  of 
headache.  She  tells  us  she  has  been  wearing  glasses  for  the  past 
ten  years,  but  they  fail  to  afford  her  much  relief.  A  member  of  the 
class  has  neutralized  them  for  us  and  tells  us  they  are  O.  D.  +  .  25 
and  O.  S.  +  .50,  both  spheres. 

We  request  her  to  be  seated  in  the  usual  testing  chair,  and 
placing  the  opaque  disk  over  the  left  eye,  we  ask  her  what  letters 
she  can  see  on  the  test  card.  She  replies  that  she  can  see  only  the 
very  large  letters,  and  in  response  to  our  request  to  be  more 
specific,  she  names  the  three  top  letters,  E  C  B,  as  the  only  ones 
she  can  see.  The  letters  C  B  you  will  recognize  as  constituting 
the  line  marked  100  feet,  and  therefore  we  will  record  the  vision  in 
this  eye  as  equaling  T\\. 

We  transfer  the  opaque  disk  from  the  left  eye  to  the  right,  and 
again  ask  the  patient  what  letters  she  can  see  on  the  card.  She 
commences  at  the  top  and  names  the  letters  correctly  until  she 
reaches  the  fifth  line,  the  one  that  is  marked  to  be  seen  by  the  nor- 
mal eye  at  40  feet.  She  hesitates,  and  as  we  encourage  her  to 
make  an  effort  to  name  the  letters  on  this  line,  she  replies  "PSO 
E. ' '  You  will  notice  that  she  has  omitted  the  middle  letter  entirely, 
and  of  the  four  she  has  named,  only  one  is  correct,  and  that  is  the 
last  one.  We  will  record  her  vision  as  ££,  modifying  the  fraction  by 
four  interrogation  points  placed  after  it,  signifying  that  four  of  the 
letters  have  been  misnamed. 

FINDING    CAUSE    OF    IMPAIRED    VISION 

As  there  is  considerable  impairment  of  vision,  our  next  step 
will  be  the  use  of  the  pin-hole  disk  in  order  to  determine  if  this  is  a 
case  that  can  be  benefited  by  glasses.  The  patient  experiences 
some  difficulty  in  getting  the  small  hole  directly  over  the  visual 
line,  but  finally  she  gets  it  into  position,  and  trying  each  eye 
separately  we  find  that  vision  of  right  eye  is  raised  from  -ffls  to  £# 
partly,  and  left  eye  from  £#  barely  to  f£  partly.  This  proves  that 
the  sight  is  susceptible  of  improvement  by  glasses  ;  otherwise,   it 


Anisometropia  79 

would  be  useless  and  a  waste  of  time  to  try  her  vision  with  test 
lenses. 

We  will  now  make  an  ophthalmoscopic  examination  to  see  if 
that  will  throw  any  light  on  the  cause  of  the  impaired  vision,  which 
even  the  pin-hole  fails  to  raise  to  normal. 

There  is  a  dimness  and  indistinctness  about  the  whole  fundus, 
while  the  optic  disk  in  each  eye  is  very  much  paler  than  normal, 
which  indicates  an  atrophied  condition  of  the  nerve.  We  would 
therefore  class  this  case  as  one  of  amblyopia  in  addition  to  any 
refractive  error  that  may  be  present. 

Before  commencing  with  any  test  lenses,  we  will  call  the 
ophthalmometer  to  our  aid.  We  fix  the  mires  so  that  they  are 
barely  in  contact  with  each  other  in  the  primary  position,  which  is 
horizontal,  and  as  we  rotate  the  instrument  the  one  mire  com- 
mences to  climb  over  the  other  until  we  reach  the  vertical  meridian, 
where  there  is  an  overlapping  of  six  steps  or  6  D.  In  the  left  eye 
there  is  also  a  marked  overlapping  in  the  vertical  meridian,  in  this 
eye  amounting  to  three  and  a  half  steps,  or  3. 50  D.  This  case  shows 
an  unusual  amount  of  corneal  astigmatism,  and  I  want  to  give  every 
member  of  the  class  an  opportunity  to  see  the  mires  overlapping 
as  they  pass  from  the  horizontal  to  the  vertical  meridian. 

In  the  examination  of  vision  with  the  test  lenses,  we  will  com- 
mence with  -J-  1  sphere  and  +  1  cylinder,  comparing  the  effect  of 
one  with  the  other.  In  view  of  the  large  amount  of  astigmatism 
shown  by  the  ophthalmometer,  we  are  not  surprised  that  patient 
rejects  the  sphere  and  accepts  the  cylinder.  We  now  increase  the 
lens  .50  D.  at  a  time  until  we  reach  +  3  D. ,  with  which  axis  at 
900  vision  equals  £#.  We  hold  a  +  .50  D.  and  a  +  1  D.  in  front 
of  the  cylinder,  both  of  which  are  rejected.  We  rotate  the  cylinder 
slightly  to  the  right  and  to  the  left,  with  the  effect  of  impairing 
vision,  so  that  we  are  justified  in  concluding  that  -f  3  D.  cyl.  axis 
900  represents  the  correction  of  the  manifest  error. 

We  cover  up  the  right  eye  and  place  +  .  50  D.  sphere  before 
the  left  :  this  is  rejected  and  we  replace  with  a  +  -5°  D.  cyl.  axis 
900,  which  also  is  rejected.  Bearing  in  mind  the  astigmatism 
which  is  revealed  by  the  ophthalmometer,  and  which  is  shown  to 
be  "with  the  rule,"  we  now  try  a  —  .50  D.  cyl.  with  axis  at  1800. 
This  is  accepted  as  affording  an  improvement  in  the  vision,  and 
we  cautiously  increase  it  .  25  D.  at  time,  until  we  reach  —  1  D.  cyl. 
axis  1800,  with  which  vision  equals  f0. 


So  •  Clinics  in  Optometry 

We  will  now  use  the  fogging  method  to  see  if  the  eyes  will 
bear  any  closer  correction.  We  have  already,  on  a  number  of 
occasions,  explained  this  method  at  some  length,  and  therefore  we 
will  not  take  the  time  on  this  occasion  to  describe  every  step,  but 
will  give  you  the  results  as  follow  : 

R.  E.,  +  3  D.  sph.  O  —  3  D.  cyl.  axis  i8o° 

L.  E.,  +  .50  D.  sph.  O  —  1.50  D.  cyl.  axis  1800 

A  comparison  of  this  formula  with  that  first  obtained  shows 
that  the  right  lens  is  equivalent  in  both  examinations.  In  the  left 
eye  we  have  succeeded  in  having  a  -f  .50  D.  sphere  accepted, 
with  a  corresponding  increase  in  the  concave  cylinder.  In  order 
that  the  two  lenses  may  correspond  as  nearly  as  possible,  we  will 
transpose  and  order  as  follows  : 

R. ,  +3  D.  cyl.  axis  900 

L. ,  —  1  D.  sph.  O  +  1.50  D.  cyl.  axis  900 

MADDOX    ROD    TEST 

We  will  complete  our  examination  with  the  test  of  the  mus- 
cular balance,  by  means  of  the  Maddox  rod  ;  which,  on  account  of 
its  poorer  vision,  is  placed  over  the  right  eye. 

We  say  to  the  patient,  by  way  of  preparing  her  for  the  test,  that 
she  sees  a  red  streak  running  up  and  down,  and  ask  her  on  which 
side  of  the  light  it  is  and  how  far  from  the  light.  She  replies  that 
it  is  on  the  left  side  of  the  light  and  that  it  is  about  an  inch  away 
from  it.  This  artificial  diplopia  we  have  produced  is  of  the  crossed 
or  heteronymous  variety,  and  we  know  that  it  indicates  an  exo- 
phoria  of  small  degree.  We  take  a  i°  prism  and  place  it  over  the 
eye  base  in,  and  the  red  streak  is  now  brought  directly  over  the 
light,  thus  showing  an  exophoria  of  i°. 

We  now  turn  the  Maddox  rod  half  way  around,  and  we  say  to 
the  patient  that  she  sees  the  red  streak  running  crosswise,  and  ask 
her  if  it  is  above  or  below  the  light  ;  she  replies  that  it  is  below  the 
light.  We  ask  her  how  far  below,  and  she  tells  us  about  one  inch. 
This  shows  a  slight  degree  of  right  hyperphoria,  which  is  corrected 
by  a  prism  base  down,  and  when  we  place  a  i°  prism  in  this  posi- 
tion it  raises  the  streak  so  that  it  runs  directly  through  the  light. 

I  want  particularly  in  this  case  to  call  your  attention  to  the 
difference  in  the  refraction  and  in  the  acuteness  of  vision  of  the  two 
eyes,   which   condition  is  known   in  optometry  as  anisometropia. 


Anisometropia  81 

This  is  not  infrequently  met  with,  and  is  usually  a  source  of  dis- 
comfort to  the  patient,  and  of  annoyance  to  the  optometrist. 

When  we  consider  that  a  very  slight  change  in  the  curvature 
of  the  cornea  or  in  the  length  of  the  eye,  causes  a  marked  variation 
in  the  condition  of  refraction,  it  is  really  to  be  wondered  at  that  the 
difference  in  any  pair  of  eyes  is  not  greater  than  is  usually  found  ; 
or,  in  other  words,  that  marked  anisometropia  is  not  more  common. 
The  statement  is  made  that  a  variation  of  \  mm.  in  the  radius  of 
the  cornea  or  of  }§  mm.  in  the  length  of  the  eyeball,  causes  a 
change  of  i  D.  in  the  refraction  of  the  eye.  And  while  it  is  seldom 
possible  to  find  two  eyes  exactly  alike,  yet  in  the  majority  of  cases 
the  difference  is  so  slight  as  to  be  detectable  only  by  a  careful 
examination,  and  therefore  small  differences  may  be  regarded  as 
more  or  less  physiological  and  calling  for  no  special  treatment.  In 
other  words,  anisometropia  would  call  for  no  special  consideration 
at  our  hands,  unless  it  caused  some  impairment  of  binocular  vision 
or  some  nervous  disturbance. 

ANISOMETROPIA 

The  term  anisometropia  signifies  nothing  as  to  the  refractive 
condition  of  either  eye.  One  may  be  emmetropic  and  the  other 
myopic  or  hypermetropic  ;  both  may  be  hypermetropic  or  myopic, 
varying  only  in  degree  ;  one  may  be  hypermetropic  and  the  other 
myopic  ;  or  one  eye  may  be  astigmatic,  or  there  may  be  a  greater 
degree  of  astigmatism  in  one  eye  than  in  the  other. 

In  the  great  majority  of  cases  anisometropia  is  a  congenital 
condition,  and  is  attributable  to  an  unequal  development  of  the  two 
eyes. 

Anisometropia  may  be  considered  under  three  different  heads: 

1.  When  binocular  vision  exists. 

2.  When  monocular  vison  exists,  the  eyes  being  used  alter- 
nately 

2.  When  monocular  vision  exists,  the  sight  being  confined  to 
one  eye. 

In  the  consideration  of  the  first  class  of  cases,  we  must  first 
prove  that  binocular  vision  really. is  present.  This  can  be  easily 
done  by  means  of  a  vertical  prism  or  the  Maddox  rod,  while 
the  patient  looks  at  the  light  across  the  room. 

When  a  prism  is  placed  before  one  eye  with  base  up  or  down, 
a  vertical  artifical  diplopia  should  be  produced  if  there  is  simultaneous 


82  Clinics  in  Optometry 

vision  ;  but  if  it  is  impossible  to  make  patient  see  two  lights  with 
any  strength  of  prism,  binocular  vision  does  not  exist. 

When  the  Maddox  rod  is  placed  before  one  eye,  if  patient  sees 
both  the  streak  and  the  light,  binocular  vision  is  present  ;  other- 
wise not. 

In  the  case  we  have  before  us,  binocular  vision  is  present  as 
proven  by  the  Maddox-rod  test  of  the  muscles,  in  spite  of  the  dif- 
ference in  the  visual  acuity  of  the  two  eyes,  and  the  character  of  the 
astigmatism,  one  being  simple  hypermetropic  and  the  other  mixed. 

In  order  that  binocular  vision  may  be  present  in  any  case  of 
anisometropia,  there  must  not  be  too  great  a  difference  in  the 
refraction,  and  this  brings  up  the  question  as  to  the  manner  in 
which  such  simultaneous  vision  is  made  possible. 

There  is  a  difference  of  opinion  among  ophthalmological 
authorities  whether  it  is  possible  to  equalize  the  refraction  of  the 
two  eyes  by  exercising  a  greater  amount  of  accommodation  in  one 
eye  than  the  other.  Some  writers  argue  that  such  is  the  case,  that 
one  ciliary  muscle  can  act  independently  of  the  other,  thus  correct- 
ing each  eye  by  a  separate  and  independent  accommodation. 

But  it  is  more  generally  believed  that  the  same  amount  of  ner- 
vous impulse  goes  to  each  ciliary  muscle,  and  hence  that  an  equal 
effort  of  accommodation  is  made  on  both  sides,  with  the  result  that 
on  one  retina  the  image  is  clear,  while  on  the  other  it  is  diffused. 
Then  the  act  of  binocular  vision  is  completed  by  the  brain  fusing  the 
blurred  image  with  the  distinct  one. 

It  follows  then  that  the  eye  which  possesses  the  greatest  visual 
acuity,  or  that  requires  the  least  accommodation,  will  play  the  chief 
part  in  the  act  of  vision,  and  that  the  other  eye  with  its  blurred 
image  will  be  a  secondary  factor,  although  it  must  be  admitted  a 
not  unimportant  one. 

VARIETIES    OF    ANISOMETROPIA 

The  second  form  of  anisometropia  is  that  in  which  the  eyes  are 
used  alternately.  One  eye  may  be  emmetropic  or  slightly  hyper- 
metropic, and  is  preferred  for  distant  use  ;  the  other  is  myopic,  and 
hence  is  adapted  for  near  vision. 

Such  a  patient  does  not  possess  binocular  vision,  but  at  the 
same  time  the  disadvantages  are  not  all  on  his  side.  Both  his  dis- 
tant and  near  vision  are  fairly  good  and  that  without  the  use  of 
glasses,  even  though  he  may  have  reached  the  presbyopic  age. 


Anisometropia  83 

The  third  variety  of  anisometropia  is  that  in  which  one  eye  is 
permanently  excluded,  and  the  other  is  used  constantly  both  for 
near  and  distance.  In  these  cases  the  inequality  between  the  eyes 
is  very  great,  the  blurred  image  formed  in  the  poorer  eye  is  ignored, 
which  eye  gradually  becomes  amblyopic  and  then  begins  to  deviate 
from  its  normal  position,  usually  inwards. 

Asthenopia  may  occur  in  cases  of  anisometropia,  and  some- 
times it  is  difficult  to  determine  whether  it  is  due  to  the  refractive 
error  that  is  always  present,  or  to  the  inequality  between  the  two 
eyes  ;  but  as  a  broad  general  rule,  we  may  state  that  anisometropic 
asthenopia  will  occur  only  in  the  first  class  of  cases,  and  is  due  to 
nerve  exhaustion  in  the  effort  to  maintain  binocular  vision  under 
disadvantageous  conditions,  as  the  images  in  the  two  eyes  differ  not 
only  in  clearness,  but  are  also  unequal  in  size. 

This  lady's  case  comes  under  this  head,  the  asthenopia  show- 
ing itself  by  a  constant  headache,  the  difference  between  the  retinal 
images  being  such  that  binocular  vision  is  maintained  only  by  a 
constant  effort  and  waste  of  nerve  energy. 

In  the  two  other  forms  of  anisometropia,  where  binocular 
vision  is  not  present,  if  asthenopia  occurs  it  must  be  due  to  the 
refractive  error  and  not  to  the  anisometropia. 

CONSIDERATIONS    IN    CORRECTION    OF    ANISOMETROPIA 

In  the  correction  of  cases  of  anisometropia,  it  should  always 
be  our  aim  to  give  the  appropriate  lens  for  each  eye.  If  the  dif- 
ference is  slight,  such  lenses  will  prove  satisfactory  ;  but  when  the 
difference  is  more  marked,  many  persons  cannot  tolerate  such  a 
correction,  partly  because  of  the  nerve  disturbance  that  is  caused 
when  an  eye  which  previously  had  borne  only  a  subordinate  part  in 
the  act  of  vision,  is  now  suddenly  called  upon  to  bear  an  equal  bur- 
den with  its  fellow,  this  being  a  great  change  from  the  condition  to 
which  the  person  had  been  for  so  long  a  time  accustomed. 

But  we  must  get  to  as  near  full  correction  for  each  eye  as  we 
can,  and  really  our  only  guide  in  this  matter  is  the  patient's  sensa- 
tions after  a  careful  trial.  In  this  case  we  feel  justified  in  ordering 
the  full  correction  in  the  expectation  that  after  the  first  two  weeks 
of  trial,  the  glasses  will  prove  satisfactory.  It  goes  without  saying, 
that  childhood  is  the  most  favorable  age  for  the  correction  of  a  case 
like  this.  It  is  most  unfortunate  that  she  was  not  properly  fitted 
ten  years  ago  when  she  first  applied  for  glasses  ;  the  simple  spheres 


84  Clinics  in  Optometry 

she  has  been  wearing  have  been  of  little  value  to  her,  and  they  cer- 
tainly are  a  reflection  on  the  skill  of  the  person  who  fitted  them. 
If  the  proper  cylinders  had  been  prescribed  at  that  time,  we  feel 
safe  in  saying  that  the  acuteness  of  vision  to-day  would  be  higher 
than  it  is. 

In  the  second  class  of  cases,  where  one  eye  is  used  for  distance 
and  the  other  for  reading,  as  a  rule  the  patient  does  not  suffer  from 
asthenopia,  and  the  attempt  to  fit  him  with  glasses  will  be  a  useless 
and  thankless  task.  Such  a  condition  of  vision  calls  for  but  little 
muscular  effort,  imposing  but  slight  tax  on  either  the  accommoda- 
tion or  convergence. 

In  the  third  class  of  cases,  any  existing  error  of  refraction  or 
accommodation  is  to  be  corrected  according  to  customary  methods, 
while  the  muscular  balance  of  the  two  eyes  or  the  refractive  condi- 
tion of  the  other  eye,  does  not  enter  into  the  question. 


Convergent  Strabismus 

[Clinic  No.   14] 

This  little  girl  (Sylvia  S. )  is  five  years  of  age.  Her  mother 
tells  us  the  left  eye  has  always  turned  in,  and  as  you  look  at  this 
child  you  have  no  difficulty  in  seeing  that  it  is  an  unmistakable  case 
of  convergent  strabismus.  For  several  weeks  past  she  has  been 
rubbing  spittle  on  her  eyes  and  complaining  to  her  mother  that 
there  is  dirt  in  them. 

The  frequency  with  which  strabismus  occurs  in  childhood,  and 
the  importance  of  a  correct  understanding  of  the  conditions  involved 
in  order  that  the  case  may  be  properly  managed,  justifies  us  in 
giving  time  to  the  careful  consideration  of  this  subject. 

Strabismus  is  usually  defined  as  consisting  of  a  deviation  of  the 
visual  axis  of  one  eye  from  the  correct  position  of  fixation.  But 
this  is  only  a  partial  definition  :  In  a  case  of  convergent  strabismus 
there  is  in  addition  to  the  abnormal  convergence,  a  defect  of  the 
fusion  faculty,  a  suppression  of  vision  in  the  eye  which  is  not  used  for 
fixation,  and  a  condition  of  amblyopia  in  the  deviating  eye,  either 
congenital  or  acquired  as  the  result  of  neglect  or  inefficient  treatment. 
There  is  also  an  error  of  refraction  present,  usually  hypermetropia. 

NATURAL    DESIRE    FOR    BINOCULAR    VISION 

In  normal  eyes  the  natural  desire  for  binocular  vision  causes 
the  visual  axes  of  the  two  eyes  to  meet  at  the  object  looked  at. 
But  if  this  desire  is  absent  or  interfered  with,  the  incentive  to  per- 
fect accord  between  the  movements  of  the  two  eyes  is  lost,  and  then 
any  slight  cause  may  disturb  the  equilibrium  of  the  convergence 
center  and  allow  the  visual  axes  to  assume  faulty  directions. 

In  order  to  see  distinctly  such  a  person  must  fix  the  object 
with  one  or  the  other  eye,  and  he  will  naturally  choose  the  eye  that 
has  the  highest  visual  acuity  or  the  lowest  error  of  refraction.  Both 
eyes  move  together,  but  both  are  not  directed  to  the  same  point. 
He  moves  his  eyes  until  he  gets  his  best  eye  in  the  desired  position, 
and  then  the  other  eye  will  be  turning  in  towards  the  nose. 

Always  remember  that  in  convergent  strabismus  both  eyes  do 
not  deviate   inwards  ;  the  good  eye  assumes  a   straight   position, 

85 


86  Clinics  in  Optometry 

while  the  poorer  eye  shows  the  convergence  of  both.  The  first  is 
known  as  the  "  fixing  eye,"  the  other  as  the  "  squinting  or  deviat- 
ing eye."  In  the  majority  of  cases  of  convergent  strabismus,  the 
separate  movements  of  each  eye  are  perfect  ;  when  one  eye  is 
covered,  the  other  can  turn  up,  down,  in  and  out  to  the  normal 
extent. 

The  natural  relation  between  accommodation  and  convergence 
is  not  disturbed,  as  proven  by  the  fact  that  when  the  fixing  eye 
accommodates  strongly  for  a  close  object,  the  deviating  eye  turns 
still  more  inwards,  proportionately  to  the  extra  effort  of  accommo- 
dation that  is  put  forth. 

CONVERGENT    STRABISMUS 

Convergent  strabismus  sometimes  occurs  as  occasional  and 
again  as  alternating  strabismus.  In  the  latter  case,  on  account  of 
each  eye  assuming  the  burden  of  vision  at  times,  the  vision  of  both 
is  good,  and  for  this  reason  such  patients  do  not  suffer  from  neglect. 

Many  of  the  students  whom  I  meet  have  the  mistaken  idea  that 
in  convergent  strabismus  because  the  two  eyes  cannot  be  directed 
to  the  same  object,  the  patient  sees  everything  double.  But  such 
is  not  the  case  ;  the  image  formed  in  the  deviating  eye  is  mentally 
ignored,  all  the  attention  being  given  to  the  image  formed  in  the 
fixing  eye.  The  patient  is  not  conscious  of  suppressing  this  impres- 
sion ;  it  is  involuntary  and  is  probably  due  to  a  defect  in  the  fusion 
faculty.  Not  only  is  diplopia  absent  in  these  cases,  but  it  is  usually 
impossible  even  to  produce  an  artificial  diplopia  by  means  of  prisms 
or  different  colored  glasses  before  each  eye. 

In  view  of  the  amblyopic  condition  of  the  retina  of  a  squinting 
eye,  the  question  has  often  been  discussed  whether  the  amblyopia 
with  its  imperfect  power  of  fixation  causes  the  deviation,  or  whether 
the  strabismus  with  its  non-participation  in  the  act  of  vision,  causes 
a  deterioration  of  the  retina  from  disuse. 

In  the  case  of  convergent  strabismus,  when  the  fixing  eye  is 
covered  the  deviating  eye  becomes  straight  and  assumes  the  act  of 
vision,  its  image  being  no  longer  suppressed.  In  some  cases  its 
vision  is  so  poor  that  fingers  can  scarcely  be  counted,  while  in 
other  cases  the  larger  letters  on  the  test  card  are  legible.  Some- 
times when  central  vision  is  almost  entirely  lost,  indirect  vision 
suffers  but  little  impairment,  and  then  by  turning  the  head  and  eye 
objects  are  seen  much  more  clearly. 


Convergent  Strabismus  S7 

ERRONEOUS    POPULAR    BELIEF 

There  is  a  widespread  belief  among  the  laity  as  to  the  spontan- 
eous cure  of  strabismus,  which  is  probably  based  upon  the  fact  that 
when  the  child  attains  his  full  growth,  the  angle  of  convergence 
becomes  less  without  any  treatment.  But  this  does  not  often  hap- 
pen, and  when  it  does  the  squinting  eye  has  by  this  time  become 
blind  from  disuse.  I  have  seen  this  occur  in  many,  many  cases 
because  the  parents  were  advised  to  wait  and  see  if  the  child  would 
not  outgrow  the  defect. 

The  age  at  which  a  convergent  strabismus  first  shows  itself  is 
an  important  point.  Statistics  prove  that  in  seventy-five  per  cent, 
of  the  cases,  the  deviation  appeared  before  the  fifth  year,  while  in  a 
very  trifling  percentage  was  its  advent  delayed  until  after  the  sixth 
year.  In  more  than  ten  per  cent,  of  the  cases  the  strabismus 
developed  during  the  first  year  of  life. 

In  regard  to  the  aetiology  of  convergent  strabismus,  many 
curious  suggestions  were  formerly  made  by  the  family  and  friends. 
Professionally,  the  first  definite  theory  attributed  it  to  a  shortening 
of  the  internal  recti  muscles,  for  which  the  natural  cure  would  be  a 
division  of  these  muscles. 

This  resulted  in  a  great  deal  of  indiscriminate  muscle  cutting, 
the  disastrous  effects  of  which  were  beginning  to  be  recognized 
when  Donders  published  his  great  work  and  gave  to  the  optical 
world  his  accommodation  theory  as  to  the  causation  of  strabismus. 

When  a  pair  of  emmetropic  eyes  are  engaged  in  distant  vision, 
the  accommodation  and  convergence  are  both  at  rest.  When  such 
eyes  are  directed  to  an  object  close  by,  they  must  converge  in  order 
that  both  visual  axes  may  meet  at  the  object,  and  at  the  same  time 
they  must  accommodate  in  order  that  the  object  may  be  seen 
clearly. 

These  two  functions,  convergence  and  accommodation,  being 
always  performed  together,  have  become  "associated,"  so  that  it 
is  difficult  (and  unnatural)  to  use  one  without  the  other. 

donder's  investigation 

An  error  of  refraction  disturbs  this  association.  A  hyper- 
metrope  must  accommodate  even  for  distance,  and  still  more  for 
near  objects.  This  unnatural  and  excessive  accommodation  tends 
to  produce  a  proportionate  abnormal  convergence.      Donders  first 


88  Clinics  in  Optometry 

recognized  this  tendency  as  the  cause  of  convergent  strabismus, 
and  he  advised  correction  of  the  hypermetropia  as  a  cure  for  the 
strabismus. 

While  this  was  a  great  advance  in  optics  at  that  day  and  led  to 
a  rational  treatment  of  this  defect,  yet  in  the  light  of  our  later 
knowledge,  we  cannot  unreservedly  accept  the  accommodation 
theory  as  the  fundamental  cause  of  strabismus. 

The  vast  majority  of  children  are  hypermetropic,  yet  only  a 
very  small  percentage  (perhaps  four  per  cent. )  develop  strabismus. 
It  has  also  been  proven  that  the  amount  of  hypermetropia  has  but 
little  to  do  with  the  question  as  to  whether  the  patient  shall  or  shall 
not  squint  in  the  first  instance,  but  when  once  strabismus  is  estab- 
lished, the  refractive  error  becomes  an  important  factor. 

We  must  go  farther  back  than  the  eye  itself  in  the  investiga- 
tion of  this  subject,  and  the  most  recent  views  show  that  the  essen- 
tial cause  of  strabismus  is  a  defect  in  the  fusion  faculty. 

THE    FUSION    FACULTY 

At  birth  we  do  not  find  the  proper  co-ordination  of  the  eyes, 
but  the  fusion  faculty  begins  to  develop  about  the  sixth  month,  and 
is  perhaps  not  complete  before  the  sixth  year.  At  first  the  instinc- 
tive desire  for  binocular  vision  will  keep  the  eyes  straight,  and 
when  the  fusion  faculty  is  fully  established,  it  is  doubtful  if  an  error 
of  refraction  can  cause  strabismus. 

Exceptionally  the  fusion  faculty  does  not  develop  until  later, 
or  develops  very  imperfectly,  or  it  may  never  develop  at  all  ;  and 
then  it  is  an  easy  matter  for  anything  that  disturbs  the  balance  of 
the  motor  co-ordination,  to  cause  a  strabismus. 

In  these  cases  then  where  there  is  a  defect  in  the  fusion  faculty, 
and  the  eyes  are  in  a  state  of  unstable  equilibrium,  ready  to  deviate 
inwards  or  outwards  on  the  slightest  provocation,  an  error  of 
refraction  such  as  hypermetropia  proves  to  be  an  important  factor, 
for  the  reasons  which  I  have  already  briefly  mentioned  to  you. 

In  the  great  majority  of  cases  of  hypermetropia,  it  cannot  be 
doubted  that  the  fusion  sense  is  unimpaired  and  hence  the  eyes  main- 
tain their  proper  positions.  But  in  the  minority  cases,  where  the 
fusion  sense  is  deficient,  there  is  no  check  to  the  tendency  to  devia- 
tion and  the  child  develops  a  convergent  strabismus. 

At  first  the  strabismus  is  occasional,  manifesting  itself  only 
when  the  child  is  looking  intently  at  some  close  object,  and  disap- 


Convergent  Strabismus  89 

pearing  when  the  accommodation  relaxes.  It  is  at  this  period  that 
the  proper  convex  lenses  to  correct  the  hypermetropia  are  of  the 
greatest  value.  But  if  the  case  is  neglected,  the  excessive  conver- 
gence becomes  permanent  and  the  strabismus  is  noticeable  even 
when  the  eyes  are  completely  at  rest.  At  this  time  convex  lenses 
do  not  cause  an  immediate  disappearance  of  the  deviation,  but  if 
the  wearing  of  glasses  is  persevered  in,  there  is  gradual  restoration 
of  the  normal  position. 

EXAMINATION    OF    THE    PATIENT 

We  will  now  return  to  the  examination  of  our  little  patient. 
No  tests  are  required  in  this  case  to  determine  the  presence  of  a 
deviation  or  its  character  ;  a  simple  inspection  shows  a  con- 
vergent strabismus  of  the  left  eye.  We  ask  the  child  with  both 
eyes  open  to  follow  the  movements  of  our  fingers,  and  as  the 
two  eyes  turn  equally  in  all  directions,  we  know  the  strabismus 
is  concomitant. 

The  next  step  would  be  to  estimate  the  visual  acuity,  but  this 
is  not  always  possible  in  the  case  of  young  children.  We  ask  the 
mother  if  this  child  knows  her  letters,  and  we  are  informed  that  she 
has  been  attending  a  kindergarten  school  and  is  familiar  with  some 
of  the  letters.  After  a  few  patient  trials,  we  find  that  the  visual 
acuity  is  about  \%,  and  that  she  seems  to  see  equally  well  with 
either  eye. 

A  subjective  test  in  a  child  so  young  as  this  is  scarcely  to  be 
depended  upon,  but  we  will  see  what  information  we  can  gain  from 
it.  After  several  changes  of  lenses  +  1  D.  spheres  are  accepted, 
with  which  vision  is  raised  to  \%. 

We  will  now  use  the  ophthalmometer  to  determine  the  exist- 
ence of  corneal  astigmatism,  but  the  eyes  are  in  such  constant 
motion  it  is  difficult  to  get  definite  results.  However,  we  can  see 
that  the  mires  overlap  considerably  in  the  vertical  meridian,  from 
two  to  three  steps. 

The  retinoscope,  on  which  we  must  chiefly  depend  in  estimat- 
ing the  refraction  in  young  children,  reveals  a  hypermetropia  of 
1.50  D.  in  the  horizontal  meridian  and  1  D.  in  the  vertical  meri- 
dian, thus  showing  a  compound  hypermetropic  astigmatism  with 
the  rule. 

The  ophthalmometer  indicates  a  higher  degree  of  astigmatism 
than  the  retinoscope,  but  as  we  are  unable  to  verify  our  findings  by 


90  Clinics  in  Optometry 

a  subjective  examination,  we  will  use  our  judgment  and  order  the 
following  as  the  refractive  correction  : 

-f  .50  D.  sph.  O  -{-  .50  D.  cyl.  axis  90°. 

USE    OF    PRISMS 

In  strabismus  seldom  can  we  measure  the  amount  of  deviation 
by  prisms,  for  the  reason  that  the  image  formed  in  one  eye  is  sup- 
pressed and  the  vision  is  monocular.  However,  in  this  case  we  are 
more  fortunate,  for  when  we  place  a  Maddox  rod  over  the  left  eye, 
the  child  sees  the  red  streak  way  off  to  the  left,  and  the  light  in  its 
proper  position.  This  indicates  a  high  degree  of  esophoria,  and 
we  commence  with  weak  prisms,  bases  out,  which  bring  the  streak 
and  light  closer  until  finally  we  reach  a  200  prism,  with  which  the 
streak  is  directly  through  the  light  as  far  as  we  can  depend  upon 
the  answers  of  our  little  patient. 

This  would  ordinarily  call  for  an  increase  in  the  strength  of  the 
convex  spheres,  but  as  this  would  blur  the  vision  at  first,  the  child 
would  be  inclined  to  reject  the  glasses.  She  cannot  understand  the 
value  of  the  glasses,  or  the  reason  for  which  they  are  given,  and  if 
she  found  she  could  see  better  without  them,  she  would  probably 
refuse  to  wear  them. 

Therefore  we  will  rely  on  a  prismatic  correction  of  the  deviation 
to  a  partial  extent,  and  will  order  a  20  prism  base  out  over  each  eye 
to  be  combined  with  the  sphero-cylinder.  We  will  direct  these  glasses 
to  be  worn  constantly,  and  tell  the  mother  that  they  should  never 
be  removed  except  for  toilet  purposes  and  when  the  child  is  in  bed. 

It  is  sometimes  necessary  to  prescribe  glasses  for  children  even 
younger  than  this.  Some  authorities  claim  that  no  infant  is  too 
young  to  wear  glasses  when  required,  even  if  not  more  than  twelve 
months  old,  but  in  my  own  experience  I  have  never  ordered  them 
in  a  child  less  than  three  years  old.  Of  course,  such  young  children 
often  break  their  glasses,  but  I  have  never  known  the  eye  to  be 
injured  thereby.  The  lens  being  confined  by  the  frame  does  not  break 
into  pieces,  or  if  it  does  they  are  not  dislodged  from  the  frame. 

We  will  direct  the  mother  to  have  this  child's  eyes  examined 
once  a  year,  and  in  this  was  we  can  probably  keep  the  strabismus 
under  control  and  prevent  either  eye  from  becoming  amblyopic, 
with  the  result  that  the  child  will  attain  maturity  with  a  pair  of  ser- 
viceable eyes.  Whereas,  if  a  case  like  this  is  neglected,  the  strabis- 
mus becomes  fixed  and  the  sight  of  the  deviating  eye  is  lost. 


Divergent  Strabismus 

[Clinic  No.  15] 

In  looking  through  the  cases  that  have  assembled  at  the  clinic 
to-day,  we  will  pick  out  this  young  man,  because  we  notice  that  he 
presents  a  marked  divergence  of  one  eye,  and  therefore  he  will 
probably  prove  to  be  an  interesting  case  ;  at  any  rate,  he  will  serve 
to  complement  the  little  girl  we  examined  at  our  last  meeting,  in 
which  there  was  a  marked  convergence  of  the  visual  axes. 

H.  K.,  aged  twenty,  telegraph  operator,  complains  of  twitch- 
ing of  eyes,  photophobia,  lachrymation  and  pain  after  reading. 

We  see  the  patient  is  already  wearing  glasses,  which  we 
neutralize  with  the  following  result  : 

R.,  +  1  S.  O  +  1.50  cyl.  axis  T200  ;  L.,  -f  .75  S.  As 
these  lenses  have  been  prescribed  by  a  very  competent  optometrist, 
they  are  probably  not  far  from  right. 

In  determining  the  acuteness  of  vision  of  the  right  eye,  in 
answer  to  our  query  the  patient  names  four  of  the  five  letters  on  the 
number  forty  line.     We  therefore  record  the  acuteness  of  vision  as 

20  > 

tit- 

METHOD    OF    EXAMINATION 

We  place  a  +  .50  sphere  in  front  of  the  eye,  and  patient  is  in 
doubt  whether  it  affords  any  improvement.  We  replace  it  with  a 
-f  .  50  cyl.  axis  vertical,  which  is  at  once  preferred  as  affording  the 
greater  acuteness  of  vision.  Leaving  this  +  .50  cylinder  in  the 
trial  frame,  we  place  in  front  of  it  another  +  .  50  cylinder  with  axis 
in  same  position,  and  alternate  with  a  +  .50  S.  in  order  that  patient 
may  decide  which  affords  the  better  vision.  The  cylinder  is 
unquestionably  preferred,  and  hence  we  replace  the  -f-  .50  cylinder 
with  a  +  1  cylinder. 

We  now  rotate  the  cylinder  first  to  the  left,  which  patient  says 
makes  vision  much  worse  ;  then  to  the  right,  which  is  accepted  as 
affording  better  vision.  After  a  few  trials,  we  find  that  the  proper 
position  for  the  axis  of  the  cylinder  is  no°. 

We  now  have  a  +  1  cyl.  axis  1  io°  over  the  right  eye,  which 
improves  vision  to  f$.  We  repeat  the  procedure  we  went  through 
a  moment  ago,  viz.  ;  placing  in  front  of  this  lens  alternately  a  + 


92  Clinics  in  Optometry 

.  50  cyl.  and  a  +  .  50  sphere.      The  cylinder  is  three  times  accepted 
and  the  sphere  once,  which  gives  us  the  following  result  : 

+  I  S.  O  +  2  cyl-  axls  no°,  with  which  vision  is  f-g-  clearly. 

In  comparing  this  lens  with  the  one  he  is  wearing,  you  will 
notice  that  the  cylinder  is  .50  D.  stronger,  and  that  the  axis  is  io° 
nearer  the  vertical.  As  we  have  made  our  examinations  carefully, 
and  as  the  gradual  increase  in  the  strength  of  the  lenses  was 
accepted  without  hesitation,  we  feel  that  our  stronger  cylinder  is 
correct. 

In  order  to  determine  with  accuracy  the  position  of  the  axis  of 
the  cylinder,  we  will  call  to  our  aid  the  ophthalmometer.  This 
instrument  shows  an  overlapping  of  2.50  D.  at  no°,  which  proves 
that  this  is  the  meridian  of  greatest  curvature,  while  the  meridian 
of  least  curvature  must  be  at  200.  This  verifies  the  result  of  the 
test  by  the  trial  case,  as  to  the  strength  of  the  cylinder  and  the 
proper  position  of  the  axis. 

As  we  turn  to  the  examination  of  the  left  eye,  we  are  struck 
with  the  marked  divergence  of  its  visual  axis.  None  of  the  letters 
on  the  test  card  can  be  seen,  even  though  we  walk  the  patient  up 
to  within  two  or  three  feet  of  the  card.  The  vision  of  this  eye  is 
reduced  to  the  counting  of  fingers  at  fifteen  inches. 

We  try  the  pin-hole  disk,  and  we  try  a  few  convex  and  con- 
cave lenses,  but  the  eye  does  not  respond  in  the  slightest  particular. 
This  forces  us  to  the  conclusion  that  this  eye  is  amblyopic,  that  it 
is  beyond  the  reach  of  optical  assistance  and  also  probably  of  medi- 
cal help. 

THREE    INTERESTING    FEATURES 

This  case  combines  in  itself  three  interesting  features  :  com- 
pound hypermetropic  astigmatism,  monocular  vision,  divergent 
strabismus,  to  the  latter  of  which  we  will  give  a  few  moments' 
attention. 

In  the  first  place,  we  wish  to  determine  whether  this  case  is  one 
of  concomitant  or  paralytic  strabismus.  We  hold  our  finger 
directly  in  front  of  patient  and  ask  him  to  look  intently  at  it.  We 
now  move  it  slowly  first  to  the  right  and  then  to  the  left,  and  ask 
patient  to  follow  with  his  eyes  the  movements  of  the  finger.  In 
doing  this  the  squinting  eye  follows  the  good  eye  in  all  its  move- 
ments, which  shows  that  there  is  no  paralysis  of  any  of  the  muscles, 
and  that  the  strabismus  can  be  classed  as  concomitant. 


Divergent  Strabismus  93 

At  our  last  meeting  we  found  that  convergent  strabismus  is 
usually  associated  with  hypermetropia,  on  account  of  the  close  con- 
nection between  the  accommodation  and  the  convergence.  And 
now  for  the  same  reason  I  wish  to  state  that  divergent  strabismus  is 
usually  associated  with  a  myopic  condition  of  the  refraction,  the 
history  of  a  typical  case  being  somewhat  as  follows  : 

As  soon  as  the  child  begins  to  attend  school,  it  is  found  that 
he  has  difficulty  in  seeing  the  blackboard,  perhaps  is  unable  to  see 
a  single  mark  upon  it.  He  is  then  given  a  front  seat,  and  the  mat- 
ter is  allowed  to  go  at  that. 

A  few  years  later  his  myopia  has  increased  so  much  that  he  is 
compelled  to  hold  his  book  very  close,  and  nothing  can  be  seen 
upon  the  blackboard  unless  he  is  allowed  to  approach  close  to  it. 

The  close  position  of  his  book  places  an  unnatural  tax  upon 
the  convergence.  He  complains  that  words  run  into  each  other, 
and  he  soon  tires  of  close  work.  About  this  time  he  accidentally 
discovers  that  by  closing  one  eye  he  can  read  comfortably  with  the 
other.  This  encourages  him  to  unconsciously  give  up  the  effort  of 
binocular  vision  by  allowing  one  eye  to  deviate  outwards,  thus  per- 
mitting him  to  read  without  effort  with  the  other  eye. 

At  first  there  is  no  actual  divergence,  only  a  failure  of  conver- 
gence with  one  eye  and  monocular  vision  with  the  other.  This 
non-use  of  convergence  weakens  this  function,  so  that  either  eye 
diverges  when  screened.  In  these  cases  there  is  no  diplopia  when 
reading,  because  the  deviating  eye  takes  no  part  in  the  act  of  vision. 

In  the  beginning,  when  the  boy  looks  up  from  his  book,  the 
divergent  eye  recovers  itself.  After  a  time  as  the  habit  becomes 
confirmed,  the  eye  remains  divergent  even  in  distant  vision. 

TREATMENT    OF    THE    CASE 

The  treatment  of  a  case  of  this  kind  consists  in  an  accurate  cor- 
rection of  the  myopia.  The  glasses  should  be  worn  constantly, 
both  for  near  and  distant  vision.  The  patient  may  complain  at  first 
that  the  glasses  make  print  very  small,  and  so  they  do  in  contrast 
with  the  large  diffused  image  formed  in  the  uncorrected  myopic 
eye  ;  but  patients  soon  become  accustomed  to  them,  particularly 
children. 

If  the  wearing  of  glasses  is  postponed  until  late  in  life,  the 
accommodation  becomes  weak  from  want  of  use,  and  in  such  cases 
it  may  be  necessary  to  order  an  additional  pair  for  reading,  2  D.  or 


94  Clinics  in  Optometry 

3  D.  weaker  than  the  distance  glasses.  Weaker  glasses  for  read- 
ing must  also  be  prescribed  in  the  higher  grades  of  myopia. 

In  recent  cases  glasses  which  afford  a  normal  acuteness  of 
vision  usually  cause  a  rapid  disappearance  of  the  strabismus,  and 
exceptionally  also  in  cases  that  have  lasted  for  years.  But  in  many 
cases  where  the  deviation  has  existed  for  some  time,  which  means  a 
prolonged  disuse  of  the  convergence,  this  function  has  become  a 
negative  quantity,  and  the  tendency  to  divergence  cannot  be  over- 
come. When  the  glasses  are  worn  with  both  eyes  open,  the  fusion 
faculty  prevents  any  deviation,  but  if  one  eye  be  covered  for  a 
moment,  it  will  diverge  and  remain  divergent  for  a  few  seconds 
after  the  removal  of  the  cover. 

This  is  a  picture  of  the  course  of  a  typical  case  of  divergent 
strabismus  caused  by  myopia,  and  it  is  well  that  you  should  have  a 
clear  understanding  of  it,  but  the  case  under  consideration  does  not 
come  under  this  head.  Here  the  divergence  dates  from  infancy, 
and  there  is  a  total  absence  of  the  fusion  sense.  The  association 
between  convergence  and  accommodation  has  been  totally  destroyed, 
as  shown  by  a  divergent  strabismus  in  connection  with  a  hyperme- 
tropic condition  of  refraction. 

In  many  cases  the  patient  has  the  power  by  a  considerable 
effort  of  convergence  to  correct  the  faulty  position  of  the  divergent 
eye,  but  with  a  relaxation  of  such  effort  the  eye  at  once  diverges, 
and  the  patient  soon  finds  that  this  is  the  most  comfortable  posi- 
tion. The  power  of  rotation  of  each  eye  separately  in  this  young 
man  we  find  to  be  normal  in  every  direction,  but  it  is  more  than 
likely  as  time  goes  on  that  the  power  of  inward  rotation  will  be  very 
much  lessened. 

This  left  eye  is  practically  blind,  and  it  is  an  interesting  fact 
that  when  both  eyes  are  blind,  they  almost  invariably  diverge. 
But  on  the  other  hand  when  only  one  eye  is  blind,  the  direction  of 
its  deviation  will  depend  to  a  great  extent  upon  the  refraction  of  the 
seeing  eye.  In  accordance  with  this  rule,  the  strabismus  in  this 
case  ought  to  be  convergent  ;  but  the  fact  that  it  is  divergent 
instead,  makes  the  case  unique  and  exceptional. 

In  this  connection  I  may  mention  an  interesting  point,  and 
that  is  in  some  cases  of  convergent  strabismus  in  which  the 
deviating  eye  has  become  amblyopic,  this  blind  eye  in  after 
years  may  become  divergent  without  any  tenotomy  having  been 
performed. 


Divergent  Strabismus  95 

MEASURING    THE    DEGREE    OF   STRABISMUS 

The  measurement  of  the  degree  of  strabismus  is  a  matter  con- 
cerning which  optical  students  have  confused  ideas.  On  asking 
them  this  question,  many  of  them  answer  "by  prisms."  Now  the 
fact  is  that  very  seldom  can  the  amount  of  strabismus  be  measured 
by  a  prism,  for  the  reason  that  the  vision  is  monocular.  If  both 
eyes  participated  in  the  act  of  vision,  diplopia  would  always  be 
present  in  strabismus,  and  then  the  prism  that  would  fuse  the  two 
images  would  represent  the  degree  of  deviation.  This  would  be 
very  simple,  but  unfortunately  in  the  majority  of  cases  of  strabis- 
mus, the  vision  of  the  squinting  eye  is  suppressed,  and  then  there 
is  no  field  for  a  prism. 

The  simplest  way  to  take  the  measure  of  a  strabismus  is  by 
the  angle  of  deviation  of  cornea,  which  is  most  conveniently  done 
by  the  perimeter.  While  this  serves  all  practical  purposes,  I  might 
say  that  this  measurement  determines  the  apparent,  and  not  the 
real  strabismus.  In  many  cases  it  is  not  important  to  differentiate 
between  the  two  ;  especially  when  the  squinting  eye  is  incapable  of 
fixation. 

You  are  all  familiar  with  the  appearance  of  the  perimeter. 
The  patient  is  seated  at  the  instrument,  which  we  adjust  so  as  to 
bring  this  left  eye  accurately  in  the  center  of  the  perimetric  arc, 
while  we  tell  the  patient  to  look  at  some  distant  object  with  the 
other  eye.  I  now  take  this  lighted  candle  which  I  move  along  the 
arc  until  I  see  the  image  of  the  flame  as  reflected  from  the  cornea  in 
the  center  of  the  pupil  of  the  deviating  eye.  Assuming  that  the 
visual  line  passes  directly  through  the  center  of  the  pupil,  the  num- 
ber of  degrees  marked  on  the  arc  corresponding  to  the  position  of 
the  flame,  will  represent  the  measure  of  the  strabismus  in  degrees. 
In  this  case  it  is  300. 

This  young  man  must  take  good  cure  of  his  right  eye,  and  we 
will  therefore  order  the  sphero-cylindrical  correction  we  found  best 
suited  to  it.  We  fear  the  left  eye  is  and  always  will  remain  useless 
as  an  organ  of  vision.  However  for  cosmetic  reasons  and  in  order 
to  remove  the  deformity  and  allow  the  eye  to  act  under  more  nor- 
mal conditions,  I  will  recommend  an  operation  in  this  case. 

One  of  two  operations  may  be  performed,  tenotomy  of  the 
_ej^rjaaLxeCJtUS,  or  advancement _of  the  infprnaLrertug  ;  but  in  this 
case  I  think  it  will  be  necessary  to  do  both  operations  at  the  same 


96  Clinics  in  Optometry 

time  in  order  to  overcome  the  excessive  divergence  and  maintain 
the  eye  in  the  proper  position. 

Diplopia  often  occurs  immediately  after  a  strabismus  operation, 
but.  is  soon  succeeded  by  single  binocular  vision  in  a  short  time  if 
the  operation  has  been  done  with  proper  care.  But  in  this  case,  on 
account  of  lack  of  vision  in  the  squinting  eye,  we  need  not  fear  any 
such  contingency  ;  but  at  the  same  time  we  do  not  wish  to  produce 
a  condition  of  convergent  strabismus  instead,  although  the  latter  is 
really  less  disfiguring  than  the  divergent  form. 

It  is  impossible  to  predict  what  might  have  been  the  result  if 
this  case  had  been  operated  in  infancy.  It  is  not  beyond  the 
range  of  possibility  that  with  the  straightening  of  the  eye  binocular 
vision  might  have  been  produced,  and  by  functional  use  the  acute- 
ness  of  vision  of  the  eye  been  raised  to  normal  and  maintained 
there. 


Headache  in  Connection  with  Myopia  and  Exophoria 


[Clinic  No.  16] 

Miss  J.  C. ,  aged  thirty-three  years,  complains  of  headache  as 
soon  as  she  begins  to  use  her  eyes  for  close  work. 

In  addition  to  the  symptoms  of  which  patient  complains,  it  is 
advisable  for  you  to  get  a  history  of  the  case,  more  or  less  com- 
plete as  its  seriousness  may  demand  ;  this  will  often  enable  you  to 
get  a  better  understanding  of  the  case  than  would  be  possible 
without. 

In  meeting  a  patient  for  the  first  time,  the  proper  question  for 
you  to  start  with  is  :  "In  what  way  do  your  eyes  trouble  you  ? ' ' 
The  most  common  answer  to  this  question  is  "headache." 

Then  you  must  make  more  specific  inquiries  so  as  to  get  more 
definite  knowledge  of  this  one  symptom  of  which  so  many  persons 
complain. 

In  what  part  of  the  head  is  it  located?  Is  it  in  the  forehead, 
in  the  temples,  in  the  vertex,  in  the  occiput,  or  does  the  whole 
head  seem  to  ache  ? 

At  what  time  of  the  day  does  the  headache  come  on — in  the 
morning,  in  the  afternoon  or  in  the  evening?  Does  the  patient 
get  up  with  it,  or  does  it  come  on  later  in  the  day  ?  Is  the  head- 
ache constant,  or  is  it  periodic  ?  Does  it  come  on  during  or  after 
use  of  the  eyes  ?  Does  it  cease  when  the  eyes  are  rested,  or  is  it 
absent  altogether  when  the  eyes  are  not  used  ?  Is  it  better  or 
worse  on  Sundays  as  compared  with  other  days  ?  Does  the  head- 
ache come  on  when  shopping,  when  riding  in  cars,  when  attending 
a  public  place  of  amusement,  or  when  in  a  crowd  ? 

HEADACHES    AND    EYESTRAIN 

No  argument  is  needed  to  convince  you  of  the  frequent 
dependence  of  headache  upon  eyestrain.  The  cure  of  headache, 
oftentimes  stubborn  and  of  long  standing,  by  the  correction  of 
errors  of  refraction  and  of  muscular  anomalies,  is  a  matter  of  almost 
every-day  experience  with  the  optometrist  in  active  practice. 

These  two  sources  of  eyestrain  are  so  often  associated  that  it 
is   really   difficult   to    determine    their   relative   importance,    some 

97 


98  Clinics  in  Optometry 

authorities  attaching  greatest  weight  to  the  strain  of  the  ciliary 
muscle  caused  by  refractive  errors,  while  others  look  upon  anomalies 
of  the  extra-ocular  muscles  as  the  greater  disturbing  factor. 

But  at  the  same  time  we  must  not  allow  ourselves  to  think  that 
every  patient  who  complains  of  headache  is  suffering  from  eye- 
strain. We  must  not  regard  every  case  of  headache  as  invariably 
due  to  a  faulty  condition  of  the  eyes,  nor  must  we  delude  ourselves 
with  the  thought,  that  glasses  can  cure  all  headaches. 

With  these  two  thoughts  in  mind  that  headaches  may  be  due 
to  eyestrain,  and  that  they  may  be  caused  by  other  conditions  of 
the  body  entirely  separate  from  the  eyes,  a  careful  and  thorough 
examination  of  the  eyes  should  be  made  in  all  cases  of  continuous 
or  frequent  headache,  where  the  cause  of  the  same  is  not  evident, 
and  where  the  usual  medical  treatment  has  failed  to  afford  relief. 

In  many  of  these  cases  the  patient  is  not  conscious  of  any 
visual  defect  or  asthenopic  symptoms,  and  is  apt  to  assert  that  his 
eyes  are  all  right  and  that  there  is  no  use  to  make  an  examination 
of  them.  In  spite  of  this  it  has  been  my  frequent  experience  that 
an  examination  has  disclosed  some  refractive  or  muscular  anomaly 
that  has  evidently  been  the  cause  of  the  headache,  as  has  been 
proven  by  the  fact  that  the  correction  of  the  former  has  been  fol- 
lowed by  a  disappearance  of  the  latter.  Experiences  like  this 
emphasize  the  importance  of  an  ocular  investigation  in  every  case 
of  headache,  even  if  there  are  no  eye  symptoms  present. 

MANY    CAUSES    OF    HEADACHE 

Therefore,  it  is  the  province  of  the  optometrist  to  find  out  just 
what  part  the  eyes  take  in  the  causation  of  headache,  and  not  as  a 
matter  of  routine  expect  to  cure  with  glasses  every  case  of  head- 
ache, a  considerable  number  of  which  may  have  no  direct  relation 
to  the  eye. 

A  browache,  due  to  malaria,  may  be  mistaken  for  ocular  head- 
ache. Hemicrania,  or  migraine,  or  sick-headache,  may  be  an 
expression  of  general  nervous  exhaustion  and  may  bear  no  relation 
to  the  eyes  at  all.  We  are  keeping  well  within  the  bounds  of  truth 
when  we  say  that  at  least  one-half  of  all  headaches  are  due  to  eye- 
strain. Gould  claims  that  seventy-five  per  cent,  of  all  headaches 
are  caused  by  a  faulty  condition  of  the  eyes. 

The  position  and  character  of  ocular  headaches  vary  greatly. 
It  may  be  sirnply  a  slight  aching  or  dull  pain  over  the  eyes,  or  at 


Headache  in  Connection  with  Myopia  and  Exophoria  99 

the  back  of  the  orbit.  It  may  be  an  occipital  pain,  which  is  sug- 
gestive of  congestion  of  the  base  of  the  brain.  Sometimes  the 
headache  is  stationary  in  the  forehead,  or  vertex,  or  occiput,  or  it 
may  originate  in  the  brows  and  pass  to  the  vertex,  shooting  to  the 
occiput  and  perhaps  even  down  the  spine. 

Some  authorities  assert  that  in  ciliary  strain,  the  pain  is  gener- 
ally orbital  and  frontal  ;  and  when  the  strain  is  on  the  extra-ocular 
muscles,  the  pain  is  occipital  and  spinal  ;  and  that  temporal  headache- 
is  due  to  astigmatism,  but  I  do  not  attach  much  importance  to  these 
classifications. 

The  location  of  the  pain  in  200  cases  of  ocular  headache  has 
been  divided  as  follows  :  Eyebrows,  41  per  cent.  ;  vertex,  20  per 
cent.  ;  occipital,  12  per  cent.  ;  occipito-frontal,  8  per  cent.  ;  tem- 
poral, 8  per  cent.      In  one  case  the  headache  was  general. 

It  should  be  remembered  that  the  position  may  vary  with  the 
individual.  Some  persons  when  they  have  a  headache,  no  matter 
from  what  cause,  always  describe  it  as  frontal,  others  as  vertical, 
and  so  on.  So,  that  too  much  dependence  must  not  be  placed  on 
the  statements  of  the  individual.  The  commonest  form  of  asthe- 
nopic  headache  is  a  dull  pain  over  one  or  both  brows,  as  shown  by 
the  analysis  of  the  200  cases  to  which  I  have  just  referred. 

THE    PATIENT'S    HISTORY 

In  getting  a  patient's  history,  you  must  not  fail  to  inquire  if  he 
or  she  has  ever  worn  glasses,  and  if  so,  how  long  and  with  what 
effect?  Make  a  record  also  of  the  character  and  strength  of  the 
lenses,  and  whether  they  were  prescribed  with  or  without  the  use  of 
"drops."  It  is  well  for  us  to  know  whether  the  eyes  have  been 
relieved  by  the  use  of  the  glasses,  or  whether  the  same  symptoms 
continue  as  were  present  before  glasses  were  worn. 

This  patient  tells  us  that  she  has  been  wearing  glasses  twelve 
years,  that  they  were  ordered  after  the  use  of  a  mydriatic,  and  that 
while  they  have  been  of  some  benefit  to  her,  the  headaches  have 
continued  and  she  suffers  after  use  of  the  eyes  for  close  vision. 

We  ask  one  of  the  young  gentlemen  to  neutralize  these  lenses, 
and  he  tells  us  they  are  —  5.50  D.  for  right  eye,  and  —2D.  for 
left  eye.  We  ask  him  if  they  were  simple  spheres,  and  he  replies 
very  emphatically  that  they  are.  We  return  them  to  him  and 
insist  on  a  more  careful  examination  and  neutralization.  In  look- 
ing through  the  left  lens  at  the  straight  edge  of  the  test  card,  he 


ioo  Clinics  in  Optometry 

finds  there  is  some  displacement  when  viewed  through  the  optical 
center  of  the  lens.  This  proves  the  presence  of  a  prism,  which  we 
find  to  be  i°  placed  in  frame  base  in. 

In  neutralizing  lenses  with  the  trial  case,  a  weak  prism  is  very 
easily  overlooked  ;  when  a  stronger  prism  is  combined,  the  shape 
of  the  edges  discloses  its  presence.  When  we  use  the  lens  measure, 
we  find  that  one  surface  is  plane  and  the  other  curved,  and  this  at 
once  raises  the  suspicion  that  the  lens  is  something  more  than  a 
simple  sphere,  and  we  are  then  led  to  look  for  a  prismatic  element. 

MEASURING    ERROR    OF    REFRACTION 

We  now  proceed  to  measure  the  error  of  refraction  by  trial 
lenses,  in  accordance  with  the  methods  which  I  have  so  often 
described  to  you,  with  the  following  result  : 

O.  D.  —  5.50  S.  O  —  .50  cyl.  ax.  900  =  f£  ?  ?  ? 
O.    S.  —  2  S.  =  f£  ?  ? 

It  is  impossible  with  any  lens,  or  any  combination  of  lenses,  to 
raise  the  vision  to  \%  full.  The  lenses  mentioned  above  afford  the 
sharpest  acuteness,  and  you  will  notice  they  differ  but  little  in  focal 
strength  from  the  lenses  she  is  at  present  wearing. 

Now,  you  will  remember  that  the  rule  in  myopia  is  to  give  the 
very  weakest  lenses  with  which  serviceable  vision  is  obtained,  and 
therefore  we  will  reduce  these  lenses  .50  D. ,  which  will  make  the 
prescription  read  as  follows  : 

O.  D.  —  5  S.  O  —  .50  cyl.  axis  900. 
O.  S.  —  1.50  S. 

With  these  lenses  she  is  able  to  decipher  one  or  two  letters  on 
the  No.  20  line,  so  that  they  really  afford  her  very  fair  vision,  and, 
at  the  same  time,  they  are  likely  to  be  somewhat  more  comfortable 
than  those  she  has  been  wearing.  Now,  these  glasses  correct  the 
error  of  refraction  and  answer  for  distant  vision  ;  shall  we  instruct 
her  to  wear  them  constantly  for  all  purposes,  or  will  she  require 
some  modification  for  reading  ?  Before  deciding  this  question,  let 
us  look  into  the  condition  of  the  muscle  balance. 

With  these  lenses  in  the  trial  frame,  we  place  a  Maddox  rod 
over  the  right  eye.  We  have  a  reason  for  placing  it  over  the  right 
eye,  and  that  is  because  it  is  the  more  defective  ;  the  left  eye, 
possessing  the  better  vision,  is  likely  to  be  the  fixing  eye. 


Headache  in  Connection  zviih  Myopia  and  Exophoria        ioi 

The  rod  is  placed  in  a  horizontal  position,  which  causes  the 
streak  of  light  to  appear  vertical.  We  ask  the  patient  if  she  sees 
this  red  streak  running  up  and  down,  which  side  of  the  light  it  is, 
and  how  far  from  the  light  ?  She  replies  that  she  sees  the  streak 
and  that  it  appears  to  be  a  foot  or  more  to  the  left  of  the  light. 
This  is  a  condition  of  artificial  crossed  diplopia,  which  we  know 
must  be  due  to  an  outward  deviation  of  the  eyes,  which  we  call 
exophoria.  We  place  a  prism  of  30  over  the  right  eye  base  in, 
which  she  tells  us  brings  the  streak  closer  to  the  light  but  still  on 
the  left  side  ;  prism  of  40  brings  it  still  closer  ;  while  a  prism  of  50 
base  in  brings  the  streak  directly  over  the  light. 

We  turn  the  rod  so  as  to  run  vertically,  and  we  say  to  the 
patient,  in  a  questioning  way,  that  she  sees  the  streak  now  running 
crosswise,  and  ask  her  whether  it  is  above  or  below  the  light.  She 
replies  that  it  is  about  two  inches  below  the  light,  which  we  know 
indicates  a  hyperphoria  of  this  eye.  A  prism  of  i°  base  down  cor- 
rects the  deviation  and  brings  the  streak  up  on  a  level  with  the 
light. 

We  repeat  these  tests  at  reading  distance,  using  the  same 
Maddox  rod  and  a  small  point  of  light,  where  we  find  the  exophoria 
has  increased  to  io°,  while  the  hyperphoria  remains  the  same  at 
i°.  This  is  only  what  we  expect  to  find  ;  exophoria  is  usually 
greater  at  reading  distance,  because  as  the  convergence  is_called 
moie—and— more  into,  play  its  weakness  becomes  more  and  more 
manifest. 

This  lady  is  33  years  of  age,  and  her  accommodation,  which  is 
not  very  vigorous  on  account  of  her  myopia,  is  becoming  weakened 
on  account  of  the  physiological  changes  in  the  ciliary  muscle  and 
crystalline  lens,  which  age  brings  on  ;  therefore,  both  her  accom- 
modation and  convergence  need  assistance  in  close  vision,  which 
we  afford  by  placing  a  convex  lens  of  1  D.  over  her  distance  lenses, 
and  combining  a  prism  with  the  base  in. 

We  will,  therefore,  order  for  close  use  : 

O.  D.  —  4  D.  S.  O  —  -5°  D.  cyl.  axis  900;  prism  30  base  in. 
O.  S.  —  1.50  D. 

We  place  the  prism  over  the  right  eye,  because  it  will  thus 
cause  less  disturbance  of  vision  than  if  placed  over  the  left  eye, 
which  is  the  better  eye  and  presumably  the  fixing  eye.  In  this  case 
such  a  procedure  is  better  than  dividing  the  prism  between  the  two 


102  Clinics  in  Optometry 

eyes,  and  I  would  advise  you  always  to  order  the__prisa3LQver 
the  more  defective  eye,  or  if  the  prism  is  divided^  to_._pj.are  the 
jitronger  over  the  poorest  eye. 

ANALYSIS    OF    THE    CASE 

In  analyzing  this  case,  it  is  reasonable  to  assume  that  the  head- 
ache is  due  partly  to  the  strain  on  accommodation  and  partly  to 
strain  of  the  convergence.  In  other  words,  that  the  asthenopia,  of 
which  the  headache  is  the  chief  symptom,  is  both  accommodative 
and  muscular.  This  assumption  being  correct,  we  will  naturally 
expect  the  patient  to  experience  relief  from  the  reading  glasses, 
which  are  so  combined  as  to  afford  assistance  to  both  functions. 

We  must  impress  upon  our  patient  the  necessity  of  changing 
her  glasses  whenever  she  reads  or  does  any  close  work.  This  is 
somewhat  troublesome,  and  as  she  is  able  to  see  fairly  well  with  her 
distance  glasses,  she  will  be  tempted  many  times  to  read  with 
them,  instead  of  taking  the  trouble  to  change.  But  unless  she  is 
willing  to  use  each  pair  of  glasses  for  its  own  particular  purpose, 
and  change  her  glasses  as  often  as  necessary,  she  cannot  expect  to 
be  relieved  of  her  headache. 

You  will  notice  that  I  have  corrected  only  a  small  part  of  the 
exophoria,  while  the  hyperphoria  I  have  ignored  for  the  present. 
It  is  well  to  be  slow  in  the  prescription  of  prismatic  lenses  ;  some- 
times, even  when  they  are  unmistakably  indicated,  they  fail  to 
afford  relief.  In  this  case  there  is  such  a  marked  amount  of  exo- 
phoria that  we  feel  justified  in  correcting  a  portion  of  it,  and 
especially  as  she  has  worn  prisms  before.  We  increase  the  prism 
and  place  it  over  the  right  eye  instead  of  the  left,  as  before,  in  this 
change  expecting  to  afford  greater  satisfaction,  for  reasons  already 
mentioned.  If,  after  wearing  the  glasses  for  a  sufficient  length 
of  time,  the  patient  still  complains,  I  would  consider  the  advis- 
ability of  increasing  the  prism  or  placing  another  one  before  the 
other  eye. 

For  the  same  reasons  I  may  find  it  necessary  later  to  consider 
the  advisability  of  correcting  the  hyperphoria.  When  vertical 
prisms  are  accepted,  they  often  afford  the  greatest  kind  of  relief  ; 
but  more  often  they  are  disturbing  to  vision  even  though  indicated 
by  an  existing  hyperphoria  ;  therefore,  the  vertical  prism  will  be 
held  in  reserve  until  we  see  if  we  cannot  afford  relief  by  the  glasses 
we  have  just  prescribed. 


Facultative  Hypermetropia 


[Clinic  No.  17] 

Miss  A.  R.  B. ,  aged  twenty-eight  years,  stenographer,  com- 
plains of  headache  and  frequent  styes.  Says  she  sees  a  speck 
before  the  left  eye  like  a  fly  when  in  a  bright  light.  Also  photo- 
phobia. 

We  ask  her  if  she  has  ever  worn  glasses  :  she  tells  us  she  got 
a  pair  about  three  years  ago,  but  that  she  hasn't  worn  them  much, 
as  they  proved  of  no  benefit.  We  neutralize  them  and  find  them 
to  be  +  .  50  D. 

The  first  step  in  the  examination  of  this  case  (as  it  should 
be  in  the  examination  of  any  case  of  refractive  error)  is  to 
ascertain  the  acuteness  of  vision.  We  find  that  she  can  name 
every  letter  on  the  No.  20  line  with  each  eye  separately,  although 
she  says  it  is  brighter  with  the  left  eye.  We  record  the  visual 
acuity  as  f-£. 

We  now  hand  her  the  reading  test  card,  asking  her  to  look  at 
the  small  type  (.50  D.)  at  the  top  of  card,  with  which  we  find  her 
near  point  is  6^"  and  her  far  point  20". 

WHAT    THE    SYMPTOMS    INDICATE 

Now,  what  are  we  to  suspect  in  this  case  ?  Certainly  not 
myopia,  on  account  of  the  normal  acuteness  of  vision.  The  head- 
ache, the  styes,  the  sensitiveness  to  light,  all  point  to  eyestrain, 
such  as  is  usually  caused  by  hypermetropia  or  hypermetropic  astig- 
matism. 

When  the  acuteness  of  vision  is  f  #  clearly,  we  are  not  so  likely 
to  find  astigmatism,  because  this  error  does  not  allow  of  perfect 
definition  of  objects  ;  therefore,  by  this  process  of  exclusion  we 
have  now  narrowed  this  case  down  to  probable  hypermetropia. 

How  can  we  determine  the  presence  of  hypermetropia,  and 
measure  its  amount  ?  By  two  general  methods  :  first,  subjective,  by 
the  use  of  trial  lenses,  and  dependence  upon  the  answers  of  the 
individual  under  examination.  Second,  objective,  by  the  use  of  the 
retinoscope,  in  which  the  patient  is  asked  no  questions,  the  exami- 
ner depending  solely  upon  his  own  jndgment. 


104  Clinics  in  Optometry 

We  will  ask  one  of  the  members  of  the  class  to  take  the  trial  case, 
and  ascertain  whether  the  refraction  of  this  case  is  hypermetropic, 
and  if  so  the  probable  amount  of  manifest  hypermetropia. 

He  commences  by  placing  the  opaque  disk  before  one  eye, 
and  while  this  is  usually  the  proper  way  to  examine  each  eye  separ- 
ately, yet  in  this  case,  where  both  eyes  possess  normal  vision,  it  is 
easier  and  quicker  in  our  preliminary  tests,  to  examine  both  eyes 
together. 

Our  examiner  places  a  pair  of  +  .50  D.  spheres  before  the 
eyes,  and  asks  patient  if  she  can  still  read  the  same  line,  to  which  we 
receive  an  affirmative  answer.  Just  here  I  wish  to  make  a  remark 
about  the  form  of  the  question  :  do  not  ask  the  patient  if  the  lenses 
make  vision  better.  This  would  be  the  proper  question  to  ask  in 
astigmatism  or  myopia,  where  the  vision  is  impaired  ;  but  in  hyper- 
metropia (of  the  facultative  kind),  where  the  vision  is  not  below  the 
standard,  the  proper  way  to  frame  the  question  is  whether  the 
patient  is  still  able  to  name  the  letters  on  the  same  line. 

The  lenses  are  increased  .50  D.  at  a  time  until  -f  2.50  D.  is 
reached,  when  patient  says  the  letters  are  blurred  and  she  can 
name  only  a  few  of  the  letters  on  the  No.  20  line,  and  those  only 
with  difficulty.  We  now  drop  back  to  +  2  D.  spheres,  with  which 
vision  is  f$,  and  which  represents  the  amount  of  the  manifest 
hypermetropia. 

The  ability  to  see  through  convex  lenses  at  a  distance  proves 
the  presence  of  hypermetropia,  because  such  lenses  make  parallel 
rays  of  light  convergent,  and  none  but  a  hypermetropic  eye  can 
receive  convergent  rays  ;  and  the  strongest  convex  lenses  with 
which  the  No.  20  line  remains  legible,  is  the  measure  of  the  mani- 
fest error. 

THE    OBJECTIVE    EXAMINATION 

So  far,  so  good  for  the  subjective  method,  and  now  I  will  ask 
another  member  of  the  class  to  take  his  retinoscope  and  make  an 
objective  examination. 

The  pupil  is  illuminated,  the  mirror  is  rotated  and  the  shadow 
is  seen  to  move  in  the  same  direction  as  the  movement  of  the 
mirror.  What  does  this  indicate  :  either  emmetropia  or  hyper- 
metropia. How  are  we  going  to  decide  which  is  present :  by 
placing  -f  1  D.  spheres  before  the  eyes  to  neutralize  the  distance. 
If  such  lenses  stop  the  movement,  the  case  is  one  of  emmetropia  ; 
if  the  movement  still  continues  "with,"  hypermetropia. 


Facultative  Hypermetropia  105 

Our  examiner  tells  us  the  movement  is  still  "  with  "  through  the 
-f-  1  D.  spheres  ;  we  direct  him  to  increase  the  strength  of  the 
lenses  until  the  movement  is  indistinguishable,  which  he  informs 
us  is  accomplished  by  -j-  3  D.  spheres. 

After  making  deduction  for  the  distance  at  which  the  mirror  is 
used,  the  result  of  the  retinoscopic  examination  is  2  D.  of  hyper- 
metropia. In  this  case,  therefore,  both  methods  yield  the  same 
finding,  and  the  objective  verifies  the  subjective  method. 

MANIFEST    HYPERMETROPIA 

This  case  then  is  of  manifest  facultative  hypermetropia.  Let 
me  stop  long  enough  to  explain  just  what  is  meant  by  these 
terms. 

Hypermetropia  may  be  overcome  or  concealed  by  the  invol- 
untary action  of  the  ciliary  muscle,  when  it  is  said  to  be  latent. 
When  the  accommodation  is  able  to  relax  so  that  the  compensating 
accommodation  or  a  certain  portion  of  it  may  be  replaced  by  a  con- 
vex lens  ;  in  other  words,  when  a  convex  lens  is  accepted  for  dis- 
tance, the  hypermetropia  is  no  longer  concealed,  and  is  then  said 
to  be  manifest. 

This  latter  is  the  condition  in  this  young  lady's  case  ;  the 
defect  is  overcome  and  the  vision  made  good  by  the  action  of  the 
accommodation.  But  as  convex  lenses  are  placed  before  the  eyes, 
the  accommodation  relaxes  and  its  place  is  taken  by  the  convex 
lenses,  which  in  this  case  are  +  2  D. ,  and  which  represents  the 
amount  of  the  manifest  error. 

The  proportion  of  hypermetropia  that  remains  latent  varies  in 
different  individuals  and  at  different  ages.  In  childhood  the  error 
is  usually  all  latent,  but  a  gradually-increasing  portion  becomes 
manifest  with  the  advance  of  age  and  the  lessening  of  accommoda- 
tive power,  until  in  old  age  all  the  latent  hypermetropia  has  become 
manifest. 

Manifest  hypermetropia  may  be  either  facultative  or  absolute. 
This  young  lady,  whom  we  know  to  be  hypermetropic  at  least  2  D. , 
enjoys  normal  acuteness  of  vision  without  any  correcting  lenses,  and 
she  still  has  normal  vision  with  -f  2  D.  spheres  ;  in  other  words,  her 
hypermetropia  may  be  corrected  by  these  lenses  or  by  an  equal  effort 
of  accommodation.  The  hypermetropia  is  manifest  because  die 
convex  lens  is  accepted,  and  we  call  it  facultative  because  the  error 
can  be  entirely  overcome  by  the  exercise  of  accommodation. 


106  Clinics  in  Optometry 

In  thirty-five  years  from  now,  when  this  lady  has  reached  the 
age  of  sixty-three  years,  at  which  time  the  amount  of  accommoda- 
tion at  her  disposal  will  have  been  reduced  to  nothing,  the  hyper- 
metropia  will  still  be  manifest,  but  instead  of  being  facultative,  it 
will  now  have  become  absolute.  The  vision  will  be  considerably 
impaired,  perhaps  to  y2^,  because  the  accommodation  is  no  longer 
able  to  neutralize,  and  then  the  +  2  D.  spheres  will  be  required  to 
overcome  the  error  and  raise  the  vision  to  normal. 

We  will  now  return  to  the  examination  of  our  case,  which  we 
roughly  determined  to  be  hypermetropic  and  approximated  the 
amount  of  defect.  We  must  now  test  each  eye  separately,  and  we 
can  probably  get  the  best  results  by  means  of  the  fogging  method. 

Covering  the  left  eye  with  the  solid  metal  disk  we  place  a  -f- 
5  D.  sphere  before  the  right  eye,  with  which  the  patient  can  see 
only  the  large  letters  at  the  top  of  the  card  ;  that  is,  with  this 
strong  convex  lens  vision  —  ■$>-$.  We  gradually  reduce  with  con- 
caves, increasing  .50  D.  at  a  time,  each  change  causing  an 
improvement  in  vision,  until  we  reach  —  2.50  D.,  with  which 
vision  has  been  restored  to  §#. 

Now  what  have  we  in  the  trial  frame?  +  5  D.  and  —  2.50 
D.,  which  by  algebraic  addition  equals  +  2.50  D.,  which  repre- 
sents the  amount  of  hypermetropia  as  revealed  by  the  fogging 
method.  We  try  the  other  eye  in  the  same  way,  and  with  the 
same  result,  viz.,  2.50  D.  of  hypermetropia. 

TESTING   THE    MUSCLES 

We  now  proceed  to  investigate  the  muscular  balance.  With 
these  lenses  (+  2.50  D.)  in  the  trial  frame,  we  place  a  Maddox 
rod  over  the  left  eye  in  a  horizontal  position.  We  direct  the 
patient  to  look  at  the  point  of  light  across  the  room,  saying  to  her 
that  she  will  see  a  red  vertical  streak  and  asking  her  on  which  side 
of  the  light  it  is  and  how  far  from  the  light.  She  replies  that  it  is 
on  the  right  side  of  the  light  and  about  three  inches  away.  The 
images  of  the  eye  being  crossed  indicates  exophoria,  which  is  cor- 
rected by  a  prism  base  in,  and  we  find  that  a  20  prism  brings  the 
red  streak  back  to  the  light. 

You  will  probably  recall  from  your  studies  of  muscular  imbal- 
ances that  esophoria  is  usually  associated  with  hypermetropia,  and 
exophoria  wTthTrnyopia.  In  this  case  then  we  have  an  anomalous 
condition,  exophoria  with  hypermetropia.  showing  a  disturbance  of 


Facultative  Hypermetropic  f  107, 

the  normal  relation  that  should  exist  between  the  functions  of 
accommodation  and  convergence. 

We  will  also  make  a  test  of  the  insufficiency  of  convergence  at 
the  reading  distance,  where  we  find  8°  of  exophoria,  the  so-called 
"  exophoria  in  accommodation."  This  is  not  uncommon,  in 
fact,  exophoria  is  always  greater  at  the  reading  point  than  at  a 
distance,  because  the  closer  the  object  is  held  the  greater  the 
amount  of  convergence  that  is  necessary,  and  hence  any  insuffi- 
ciency of  this  function  becomes  the  more  manifest. 

We  will  make  a  further  investigation  of  the  muscles  by  means 
of  the  duction  tests  for  determining  the  relative  power  of  conver- 
gence and  divergence. 

The  patient  is  directed  to  keep  her  eyes  fixed  on  the  light, 
while  we  place  prisms  bases  in,  gradually  increasing  their  strength 
until  diplopia  is  caused,  when  we  return  to  the  strongest  prism  base 
in  with  which  single  vision  can  be  maintained,  which  will  represent 
the  power  of  abduction  or  divergence,  which  in  this  case  we  find 
to  be  6°.     This  is  about  normal. 

Then  we  place  gradually  increasing  prisms  before  the  eyes 
bases  out  until  diplopia  is  produced,  which  we  encourage  the 
patient  to  overcome  by  looking  inwards  towards  the  nose,  by 
"trying  to  look  crossed-eyed,"  as  we  express  it,  and  we  find  that 
8°  bases  out  are  the  strongest  pnsms_with_ which  single  vision  can 
be  maintained,  and  this  therefore  is  the  measure  of  the  adduction 
or  convergence.  You  will  recall  that  the  normal  power  of  adduc- 
tion is  from  200  to  300 ;  and  therefore  in  this  case  it  is  insufficient. 
This  means  an  absolute  weakness  of  the  internal  recti  muscles, 
which  accounts  for  th^~exopHoria. 

THE    GLASSES    TO    PRESCRIBE 

Now,  then,  what  glasses  shall  we  order  for  the  correction  of  this 
case  ?  I  have  always  advised  you  to  be  slow  in  the  prescribing  of 
prisms,  and  if  possible  to  influence  the  muscular  imbalance  through 
the  refraction,  but  such  advise  will  not  hold  good  in  a  case  like  this. 
Convex  lenses  tend  to  increase  exophoria,  and  jf_we__prescribe  full 
correction  for  the  hypermetropia,  we  will  certainly  aggravate  the 
muscular  insufficieny. 

But  we  must  prescribe  convex  lenses  for  the  hypermetropia, 
not  allowing  them  to  be  too  strong  however.  I  think  +  1.50  D. 
would    be  about    right  ;  this   is    making  some  concession    to   the 


io8  Clinics  in  Optometry 

exophoria,  and  at  the  same  time  corrects  the  major  part   of  the 
error  of  refraction. 

Shall  we  dismiss  the  case  with  the  prescription  for  these  con- 
vex lenses?  No,  we  think  that  prisms  should  be  combined  with 
them  to  assist  the  convergence,  and  we  will  order  as  follows  : 

n'    (,"  [■  +  1.50  D.  S.  O  prism  i°  base  in. 

We  will  direct  these  glasses  to  be  worn  constantly,  and  we 
prescribe  them  with  the  greatest  confidence  that  they  will  afford 
relief. 

This  is  a  clear-cut  case  ;  there  is  no  doubt  as  to  the  condition 
of  the  refraction  and  the  muscle  balance.  The  patient  has  answered 
the  questions  without  hesitation  and  without  contradicting  herself, 
and  the  presence  of  hypermetropia  and  exophoria  is  fully 
established. 

The  patient  asks  us  how  long  these  glasses  will  last  her  ;  this 
is  a  question  no  one  can  answer  with  certainty.  We  would  advise 
a  re-examination  in  two  years,  and  sooner  if  the  symptoms  seem  to 
call  for  it. 


Hyperphoria 


[Clinic  No.  iS] 

A.  H.  J.,  thirty-seven  years  of  age,  a  machinist  by  occupation, 
complains  of  headaches  at  times  and  a  soreness  and  aching  in  eye- 
balls. In  reading  he  must  make  a  conscious  effort  to  adjust  his 
eyes  for  the  print.  Has  felt  for  some  time  that  his  eyes  needed 
attention,  but  has  simply  neglected  the  matter.  Has  never  had  his 
eyes  examined,  and  has  never  worn  glasses. 

We  find  the  acuteness  of  vision  a  little  better  than  normal,  as 
he  is  able  to  name  about  half  the  letters  on  the  No.  15  line.  In 
ascertaining  his  range  of  accommodation,  we  find  that  by  an  effort, 
he  is  able  to  read  the  smallest  print  as  close  as  8  inches  and  as  far 
away  as  28  inches. 

These  findings  practically  exclude  myopia  and  astigmatism,  and 
narrow  the  refraction  down  to  a  choice  between  emmetropia  and 
hypermetropia.  How  are  we  going  to  determine  which  of  these 
two  conditions  is  present  ?  The  most  practical  and  easily  applied 
methods  at  our  command  are  the  trial  case  and  the  retinoscope. 

In  using  the  test  lenses  the  diagnosis  of  hypermetropia  depends, 
of  course,  upon  the  acceptance  of  convex  lenses  for  distant  vision, 
while  the  rejection  of  the  same  would  indicate  emmetropia. 

METHOD    OF    EXAMINATION 

We  place  a  pair  of  +  1  D.  lenses  before  his  eyes,  knowing 
that  if  vision  equals  £$  or  better,  with  such  lenses,  hypermetropia  is 
present.  In  answer  to  our  question  as  to  whether  he  can  see  the 
same  line,  patient  replies  in  the  affirmative.  Mark  you,  we  do  not 
ask  if  the  glasses  make  vision  better  ;  this  is  not  the  proper  form  of 
question  when  the  vision  is  already  normal.  In  myopia,  and  even 
in  astigmatism,  where  the  vision  is  greatly  impaired,  and  where 
our  effort  is  exerted  to  raise  it  to  normal,  we  very  properly  ask 
patient  if  such  and  such  lens  improves  vision,  and  whether  one  is 
better  than  the  other.  But  in  hypermetropia,  when  the  accommo- 
dation is  able  to  maintain  the  vision  at  the  normal  standard,  there 
is  no  question  of  improving  vision  by  convex  lenses,  but  rather  the 
ability  to  see  through  convex  lenses  as  well  as  without  them. 


no  Clinics  in  Optometry 

Patient  tell  us  he  is  able  to  see  through  these  lenses  very 
clearly,  naming  the  same  letters  as  before  ;  this  proves  hyperme- 
tropia,  and  in  order  to  determine  its  amount,  we  increase  the  lenses 
.50  D.  at  a  time  until  +  2-5°  D-  is  reached,  which  produces  a 
notable  blurring  of  the  letters.  We  therefore  estimate  the  probable 
amount  of  hypermetropia  at  2  D. 

Having  thus  determined  the  condition  of  refraction  with  both 
eyes  together,  we  now  proceed  more  carefully  to  measure  the 
amount  of  defect,  by  testing  each  eye  separately. 

As  is  our  usual  custom  in  hypermetropia,  we  use  the  fogging 
system.  We  place  -f  5  D.  lens  in  front  of  the  right  eye,  with 
which  even  the  No.  200  letter  is  illegible.  We  partially  neutralize 
with  concave  spheres,  commencing  with  —  .50  D.  and  increasing 
.50  D.  at  a  time,  each  change  of  lenses  producing  a  still  further 
improvement  of  vision.  In  this  method  of  testing,  where  the  vision 
is  so  greatly  fogged  by  the  strong  convex  lenses,  it  is  perfectly 
proper  to  ask  as  we  place  the  concave  lenses  if  they  improve  vision, 
as  our  effort  now  is  to  raise  the  vision  to  normal  in  spite  of  the  con- 
vex lenses. 

When  we  reach  —  2D.  the  vision  has  become  normal,  some 
of  the  letters  in  the  No.  15  line  being  again  legible.  The  result 
of  —  2D.  placed  over  +  5  D.  is  -\-  3  D. ,  which  represents  the 
amount  of  hypermetropia  we  have  uncovered.  We  repeat  the  same 
test  with  the  left  eye,  where  we  find  2.50  D.  of  hypermetropia. 

RETINOSCOPIC    TEST 

We  will  now  turn  to  our  test  by  the  retinoscope.  The  direc- 
tion of  movement  of  the  shadow  in  both  eyes  is  unquestionably 
"with."  This  may  mean  either  emmetropia  or  hypermetropia. 
In  order  to  determine  between  these,  we  place  +  1  lenses  before 
the  eyes  ;  if  these  neutralize  the  movement,  emmetropia  is  present. 
But  if  the  movement  is  still  "with,"  the  refraction  is  hypermetropic. 

In  this  case  we  find  the  movement  is  still  in  the  same  direction, 
thus  classing  the  refraction  as  hypermetropic.  We  now  measure 
each  eye  separately,  increasing  the  strength  of  the  convex  lens  as 
long  as  the  movement  continues  "with,"  and  we  find  that  a  -f-  4 
D.  neutralizes  the  movement  in  the  right  eye,  and  a  -j-  3. 50  D.  in 
the  left  eye.  We  subtract  1  D.  to  allow  for  the  distance  at  which 
the  test  is  made,  the  result  being  exactly  the  same  as  that  found  by 
the  trial  case. 


Hyperphoria  1 1 1 

This  is  quite  a  marked  amount  of  defect,  and  it  imposes  a  tre- 
mendous tax  upon  the  accommodation,  which  at  this  age  is  scarcely 
able  to  bear  it.  A  hypermetropia  of  this  amount  at  this  age  would 
be  sufficient  to  account  for  the  headaches,  the  aching  in  eyeballs 
and  the  effort  required  to  adjust  the  eyes  for  reading. 

But  we  must  not  be  content  to  stop  here,  we  have  finished  only 
half  our  examination,  and  as  conscientious  optometrists  we  are  bound 
to  make  the  examination  of  each  case  thorough  and  complete. 

We  therefore  pass  on  to  an  investigation  of  the  muscular  equi- 
librium, for  which  we  depend  on  the  use  of  the  Maddox  rod.  This 
is  placed  before  the  left  eye  in  a  horizontal  position,  causing  this 
eye  to  see  a  vertical  streak  of  light.  In  answer  to  our  question  as 
to  which  side  of  the  light  the  streak  appears  and  how  far  from  the 
light,  the  patient  tells  us  about  a  foot  or  more  to  the  left.  This 
being  on  the  same  side  as  the  eye  over  which  the  rod  is  placed, 
indicates  esophoria,  and  is  correctible  by  prisms,  bases  out,  the 
amount  of  prism  required  being  the  measure  of  the  esophoria,  which 
in  this  case  we  find  to  be  8°  ;  in  other  words,  a  prism  of  this 
strength  is  required  to  bring  the  streak  up  to  the  light.  While  we 
would  expect  to  find  some  esophoria  in  a  case  of  hypermetropia  like 
this,  we  are  scarcely  prepared  to  find  so  much. 

We  now  turn  the  Maddox  rod  around  to  the  vertical  position, 
when  the  image  formed  in  this  left  eye  will  be  a  horizontal  streak 
of  light.  We  ask  the  patient  if  this  streak  is  above,  below  or 
through  the  light.  He  answers  that  it  is  away  below,  at  least  six 
inches.  This  indicates  a  hyperphoria  of  this  eye  and  is  corrected 
by  a  prism,  base  down.  The  degree  of  prism  required  to  bring  the 
streak  up  to  the  flame  will  be  the  measure  of  the  hyperphoria. 
We  commence  with  a  2°  prism,  which  brings  the  streak  somewhat 
closer,  but  still  considerably  below.  We  increase  to  30,  then  to 
40,  and  then  to  50,  when  patient  tells  us  the  streak  is  now  through 
the  light.  We  make  the  entry  in  our  record  book  L.  H.  (the 
abbreviation  for  left  hyperphoria),  50. 

INTERESTING    FEATURE    OF    THE    CASE 

This  throws  a  new  light  upon  the  case,  and  instead  of  being  one 
of  hypermetropia  with  its  accompanying  esophoria,  we  are  inclined 
to  regard  the  hyperphoria  as  the  essential  feature  of  the  case. 

I  have  seen  the  statement  made  by  an  optical  writer  that  in 
high  convergent  strabismus  there  is  almost  always  in  addition  an 


112  Clinics  in  Optometry 

upward  deviation  of  the  squinting  eye.  I  have  not  been  able  to 
verify  this  statement  in  my  ovvrTexperience,  but  it  is  well  for  you  to 
bear  in  mind  the  possibility  of  such  connection.  This  may  serve  to 
explain  the  hyperphoria  in  this  case  occurring  in  connection  with  a 
marked  degree  of  esophoria. 

A  hyperphoria  of  i°  is  capable  of  giving  rise  to  asthenopic 
symptoms  ;  much  more  so  than  an  equal  amount  of  esophoria  or 
exophoria,  and  therefore  this  form  of  deviation  calls  for  our  care- 
ful consideration. 

The  average^  strengthjpf  thejvejnicjd_inusclesjs_scarcely  more 
than  2°  ;  a  hyperphoria  of  i°  is  one-half  the  total  strength  of  these 
muscles,  and  hence  it  can  be  easily  understood  why  .a.  hyper- 
phoria of  this  comparatively  small  amount  is  such  a  disturbing 
factor. 

The  external  and  internal  recti,  on  the  other  hand,  are_  much 
stronger,  and  besides  "the  "action  _of_these  muscles  is  influenced  by 
the  effort  of  accommodation.  This  explains  why  a  higher  degree^ 
of  exophoria  or  esophoria  produces  much  less  marked  symptqms_of 
asthenopia.  And  then  again,  we  "can  at  least  partially  correct  the 
former  with  concave  lenses  and  the  latter  with  convex  lenses, 
through  their  action  on  the  accommodation,  but  we  have  no  such 
means  of  influencing  the  hyperphoria. 

When  we  come  to  inquire  into  the  etiology  of  hyperphoria, 
the  only  explanation  that  can  be  given  for  its  occurrence  is  that  the 
balance  of  power  between  the  superior  and  inferior  recti  muscles  of 
one  eye  differs  slightly  from  that  of  the  other. 

Hyperphoria  may  be  latent  just  as  hypermetropia  is  latent.  It 
is  that  portion  of  the  anomaly  which  the  observer  fails  to  find. 
What  is  latent  at  one  time  to  one  man,  is  manifest  to  another 
under  other  conditions.  A  relatively  greater  amount  of  defect 
may  be  latent  in  the  superior  and  inferior  recti  than  in  the 
external  and  internal  recti,  for  the  reason  that  the  latter  in  the 
performance  of  their  function  are  alternately  converging  and 
diverging  the  optic  axes,  while  the  superior  and  inferior  recti 
are  never  called  upon  to  produce  any  change  in  the  relative 
position  of  the  two  optic  axes.  Whatever  position  they  assume, 
they  must  not  deviate  from  the  same  horizontal  plane  ;  conse- 
quently, the  impluses  to  the  vertical  muscles  become  more  fixed, 
and  for  this  reason  defects  in  these  muscles  are  less  likely  to 
manifest  themselves. 


Hyperphoria  1 1 3 


TREATMENT    OF    HYPERPHORIA 


The  treatment  of  hyperphoria  may  by  optical  or  surgical.  In 
the  higher  degrees  of  hyperphoria,  an  operation  may  be  advisable, 
if  the  symptoms  are  of  sufficient  gravity  to  justify  operative  inter- 
ference, either  tenotomy  of  the  superior  rectus  of  the  hyperphoric 
eye  or  advancement  of  the  inferior  rectus.  But  even  in  these  cases 
we  would  advise  a  trial  of  prisms  first,  in  order  to  note  their  effect. 
If  prisms  do  not  afford  a  fair  measure  of  relief,  there  is  always  room 
for  doubt  whether  an  operation  will  be  any  more  successful.  For 
it  must  be  remembered,  that  the  existence  of  a  hyperphoria  cannot 
by  any  means  be  accepted  as  positive  proof,  that  this  is  the  cause 
of  the  headache,  or  asthenopia  or  other  reflex  nervous  disturbances 
of  which  the  patient  may  complain. 

In  the  optical  treatment  of  hyperphoria,  some  interesting  ques- 
tions arise  in  the  prescriptions  of  the  correcting  prisms.  In  cases 
of  i°  of  hyperphoria  a  single  prisms  suffices,  and  the  question 
occurs  over  which  eye  it  shall  be  placed.  If  the  vision  of  one  eye  is 
decidedly  poorer  than  the  other,  we  preferably  place  the  prism  over 
the  more  defective  eye.  In  cases  where  the  vision  of  the  two  eyes 
is  about  equal,  it  has  been  customary  to  place  the  prism  over  the 
left  eye.  % 

Now,  my  experience  has  been  that  a  prism,  base  down,  is  not 
so  comfortable  as  one  base  up.  In  other  words,  the  raising  of 
objects  by  the  base-down  prism  is  apt  to  cause  more  disturbance  of 
vision  than  the  lowering  effect  of  the  base-up  prism,  probably 
because  the  lines  of  vision  are  more  often  and  more  naturally  below 
the  level  of  the  eyes  than  above. 

For  this  reason,  unless  there  are  indications  to  the  contrary,  I 
think  it  is  better  to  place  the  prism  base  up  over  the  cataphoric  eye 
rather  than  base  down  over  the  hyperphoric  eye.  For  instance,  in 
a  case  of  right  hyperphoria  of  i°,  instead  of  ordering  prism  base 
down  over  right  eye  and  raising  the  vision  of  this  eye  to  the  level 
of  the  other,  I  would  order  prism  base  up  over  left  eye  and  thus 
lower  the  vision  of  this  eye  to  the  level  of  the  right. 

There  are  other  indications  for  varying  the  position  of  the 
prisms,  as,  for  instance,  the  following  :  A  case  of  left  hyperphoria, 
of  which  i°  is  shown,  when  the  Maddox  rod  is  over  the  right  eye, 
and  i}4°  when  over  the  left  eye.  In  this  case  the  right  eye  is 
probably  the  fixing  eye,  and  a  prism  of  i°,  base  up,  over  this  eye 


H4  Clinics  in  Optometry 

would  be  likely  to  cause  more  disturbance  of  vision  (at  least,  when 
first  worn)  than  one  of  base  down  over  left  eye,  for  obvious  reasons. 

NECESSITY    OF    PRISMS 

The  necessity  of  prisms  for  the  correction  of  hyperphoria  is 
often  easy  of  demonstration.  While  the  patient  looks  at  the  test 
card  through  his  refractive  correction,  a  vertical  prism  in  its  proper^ 
position  is  placed  over  one  eye  and  then  in  a  moment  reversed, 
when  the  patient  can  quickly  decide  which  position  is  comfortable 
and  which  disturbing  to  vision.  Inlhe  absence  of  such  indications, 
that  is,  inpatient  is_unable_to  decide  which  position  is  comfortable, 
aprism  would  be  of  doubtful  value. 

When  the  hyperphoria  is  2°_or  more,  it  is  customary  to  divide 
the  prism  between  the  two  eyes,  base  down  before  one  eye  and  base 
up  before  the  other.  This  applies  to  the  case  under  consideration, 
and  we  will  order  2°  base  up  right  eye  and  2°  base  down  left  eye, 
thus  depressing  the  image  of  one  eye  and  elevating  that  of  the 
other,  in  this  way  restoring  the  visual  lines  of  the  two  eyes  to  the 
same  level. 

We  are  now  ready  to  order  the  glasses  for  our  patient.  We 
must,  of  course,  prescribe  for  the  hypermetropia,  but  as  he  has 
never  worn  glasses  we  tfannot  make  them  too  strong.  Nor  do  I 
think  it  well  to  order  a  full  correction  for  the  hyperphoria.  The 
esophoria  for  the  present  can  be  safely  ignored.  With  these  con- 
siderations our  prescription  will  read  : 

O.  D. ,  -(-  2  D.  sph.  O  prism  2°  base  up, 

O.  S. ,  +  1.75  D.  sph.  O  prism  20  base  down, 

which    we   will    direct    to    be    set    in    spectacle    frames    and    worn 
constantly. 


A  Case   of  Astigmatism,   Illustrating  the  Value   of    the 
Ophthalmometer 


[Clinic  No.  19] 

Mabel  M.,  aged  sixteen  years,  in  good  general  health,  has 
a.ways  had  trouble  with  her  eyes.  Complains  of  headache,  aching 
of  eyeballs  and  dimness  of  vision. 

This  young  lady  has  been  sent  to  us  by  one  of  our  former 
students,  with  the  statement  that  he  recognizes  it  as  a  case  of  some 
difficulty,  that  it  seems  to  him  to  be  spasm  of  accommodation,  and 
that  he  does  not  wish  to  assume  the  responsibility  of  prescribing 
glasses,  as  he  confesses  he  does  not  understand  the  case. 

He  further  tells  us  that  the  girl  comes  to  him  wearing  —  .75 
D.  cylinders,  ordered  by  some  other  optician,  which  glasses  have 
proved  of  no  benefit. 

USE    OF    TEST    LENSES 

In  using  test  lenses,  we  always  commence  with  convexes  ; 
cylinders  if  astigmatism  is  present,  spheres  if  astigmatism  is  absent. 
In  the  first  examination  of  a  case,  we  do  not  know  if  the  refraction 
is  myopic  or  hypermetropic,  but  as  the  majority  of  cases  are  the 
latter,  convex  lenses  are  usually  accepted  ;  but  if  rejected,  no  harm 
is  done.  Whereas,  if  convex  lenses  are  tried  first,  they  are  very 
often  accepted  even  in  the  presence  of  hypermetropia,  especially  if 
the  error  is  not  of  high  degree. 

An  eye  instinctively  makes  an  effort  to  overcome  concave 
lenses  when  placed  in  front  of  it,  the  ciliary  muscle  is  thus  called 
into  action  and  may  result  in  spasm  of  accommodation,  which  is 
essentially  a  condition  of  false  or  artificial  myopia,  and  for  this  rea- 
son concave  lenses  are  accepted  and  cause  an  improvement  in 
vision.  Therefore,  the  fact  that  a  patient  accepts  concave  lenses  is 
not  proof  that  he  has  myopia,  because  such  lenses  really  produce  a 
condition  that  favors  their  acceptance. 

The  rule  to  always  try  convex  lenses  first  and  the  reasons 
for  it,  as  I  have  just  stated,  are  doubtless  well  known  to  you  all, 
and  yet  it  seems  necessary  to  mention  and  emphasize  them  occa- 
sionally, lest  you  become  careless  about  their  observance. 


Ii6  Clinics  in  Optometry 

We  find  the  acuteness  of  vision  in  this  case  is  |£  with  each  eye 
separately,  and  that  the  range  of  accommodation  with  small  print  is 
from  2>lA"  to  9". 

Now  here  we  have  a  case  in  which  the  distant  vision  is 
impaired  and  the  reading  is  held  close  to  the  eyes,  the  far  point 
being  located  at  9".  This  condition  of  distant  and  near  vision 
makes  us  think  of  myopia,  because  we  know  that  the  essential  fea- 
tures of  this  defect  are  an  impairment  of  distant  vision  and  a  hold- 
ing of  the  book  close  to  the  eyes. 

This  might  lead  us  to  commence  our  test  with  concave  lenses, 
presuming  the  case  to  be  one  of  myopia  ;  but  I  admonish  you  all  to 
resist  any  such  temptation  under  like  conditions. 

Let  me  call  your  attention  to  a  discrepancy  between  the 
amount  of  possible  myopia  indicated  by  the  far  point  of  reading 
vision.  With  an  acuteness  of  vision  of  ££,  there  could  not  be  a 
myopia  of  more  than  1  D.  or  1.50  D.,  whereas  a  far  point  of  nine 
inches  indicates  a  myopia  of  4.50  D.  This  discrepancy  should  at 
once  raise  your  suspicion  that  you  have  not  a  case  of  simple  myopia 
to  deal  with,  and  if  there  were  no  other  reason  should  be  sufficient 
to  prevent  you  from  beginning  your  test  with  concave  lenses. 

We  now  take  a  +  .50  D.  sphere  and  a  -f-  .50  D.  cylinder,  and 
place  first  one  and  then  the  other  over  the  right  eye,  rotating  the 
cylinder  through  the  several  meridians.  The  patient  tells  us  that 
neither  lens  or  any  position  of  the  cylinder  makes  any  difference  in 
vision  either  for  the  better  or  worse. 

This  is  not  encouraging,  but  still  we  must  not  try  concave 
lenses.  What  method  of  examination  can  we  make  use  of  to  throw 
some  light  on  this  case,  the  refraction  of  which  is  so  much  in 
doubt?  We  will  use  the  ophthalmometer.  In  my  private 
office  it  has  become  my  routine  habit  to  use  this  instrument 
after  ascertaining  the  acuteness  of  vision  and  the  range  of  accom- 
modation, and  before  commencing  with  the  trial  lenses  or  the 
retinoscope  or  ophthalmoscope. 

USE    OF    THE    OPHTHALMOMETER 

Perhaps  you  may  be  inclined  to  ask  the  reason  why  I  use  the 
ophthalmometer  so  early  in  the  examination  of  every  case,  and  my 
reply  is  that  I  wish  to  determine  the  presence  or  absence  of  astig- 
matism, and  when  this  is  done,  much  time  is  saved  and  the  case  is 

simplified. 


A  Case  of  Astigmatism  117 

Ordinary  cases  of  hypermetropia  and  myopia  are  as  a  rule 
easily  detected  and  corrected ;  but  even  here  certain  definite 
methods  of  examination  should  be  followed.  Perhaps  some  of  you 
may  think  that  the  ophthalmometer  is  not  of  any  value  in  case  of 
simple  hypermetropia  and  myopia,  but  I  hasten  to  assure  you  that 
it  is  invaluable  in  every  case  of  refractive  error  that  passes  through 
your  hands.  In  case  of  hypermetropia  and  myopia,  it  practically 
eliminates  the  question  of  (corneal)  astigmatism.  This  is  a  most 
important  matter,  for  when  we  know  that  astigmatism  is  absent, 
our  trial  case  examination  is  more  easily  and  quickly  made.  There- 
fore, even  in  simple  axial  errors,  the  ophthalmometer  is  of  great 
value  in  furnishing  negative  information. 

Astigmatism  is  one  of  the  most  common  refractive  errors,  and 
is  the  cause  of  much  trouble  both  to  patient  and  prescriber,  espec- 
ially when  occurring  in  the  compound  and  mixed  forms.  In  the 
correction  of  refractive  errors,  astigmatism  stands  first  in  import- 
ance. Therefore,  if  we  have  any  ready  method  by  which  we  can 
detect  its  presence  early  in  the  examination,  it  is  well  for  us  to  take 
advantage  of  it,  and  such  a  method  we  have  in  the  ophthalmometer. 

We  place  our  young  patient  seated  before  the  instrument, 
with  her  chin  upon  the  chin-rest  and  her  forehead  pressed  against 
the  head-rest,  so  as  to  keep  her  head  fixed  and  immovable.  Both 
eyes  wide  open,  and  the  black  cover  in  front  of  left  eye,  while  we 
ask  patient  with  right  eye  to  look  directly  into  the  telescope.  The 
two  eyes  should  be  on  the  same  level,  as  otherwise  the  least  rota- 
tion of  the  head  will  change  the  axis  50  or  io°  from  its  proper 
position,  thus  leading  the  examiner  astray  and  perhaps  throwing 
an  undeserved  blame  upon  the  instrument. 

We  now  look  through  the  telescope,  moving  it  from  one  side 
to  the  other  and  up  and  down,  until  we  have  the  cornea  in  the  cen- 
ter of  the  field.  Then  we  focus  by  moving  the  instrument  closer  to 
and  farther  from  us  until  the  mires  are  at  their  most  distinct  point. 

PRIMARY    AND    SECONDARY    POSITIONS 

Now  we  obtain  the  "primary  position,"  which  is  in  the  meri- 
dian of  least  curvature,  and  is  that  point  where  the  transverse  guide 
lines  are  coincident  and  form  one  continuous  straight  line,  thus 
indicating  the  position  of  one  of  the  principal  meridians. 

We  rotate  the  telescope  so  that  the  mires  are  in  the  horizontal 
position,  where  in  the  majority  of  cases  the  guide  lines  are  continuous. 


nS  Clinics  in  Optometry 

But  in  this  case  the  lines  are  broken,  and  we  slowly  rotate  the 
instrument  until  the  lines  become  continuous.  This  we  soon  find 
to  be  at  20°,  and  this  then  is  the  primary  position  in  this  case, 
and  one  of  the  principal  meridians.  It  is  now  necessary  to  note  the 
position  of  the  mires  ;  they  must  not  overlap  nor  must  they  be 
separated,  and  hence  we  move  them  slightly  so  that  they  are  barely 
in  contact. 

We  are  now  ready  to  obtain  the  "  secondary  position,"  which 
is  exactly  at  right  angles  to  this  and  is  the  other  principal  meridian, 
or  the  meridian  of  greatest  curvature. 

We  rotate  the  telescope  slowly,  and  we  see  the  one  mire 
creeping  over  the  other  more  and  more,  and  when  we  reach  the  one 
hundred  and  tenth  meridian,  the  guide  lines  have  again  become 
continuous,  and  the  mires  have  overlapped  to  the  extent  of  five 
steps  or  5  D. 

We  can  now  place  the  blind  in  front  of  the  right  eye,  and  turn 
the  telescope  so  as  to  cover  the  left  eye.  Going  through  the  same 
steps  as  with  the  other  eye,  we  find  the  primary  position  to  be  at 
1600,  and  the  secondary  position  at  700,  where  the  mires  overlap  to 
the  extent  of  five  steps  or  5  D. 

Now  what  have  we  found  :  we  have  ascertained  the  presence 
of  astigmatism,  the  amount  of  astigmatism,  the  location  of  the  meri- 
dians of  least  and  greatest  curvature,  and  the  position  of  the  axis  of 
the  correcting  cylinder. 

As  to  the  amount  of  astigmatism  as  indicated  by  the  ophthal- 
mometer and  the  strength  of  the  cylinder  accepted  by  the  patient, 
some  little  allowance  must  be  made.  In  astigmatism  ' '  with  the  rule, 
the  ophthalmometer' s  indication  is  from  .50  D.  to  1  D.  greater 
than  it  should  be,  whereas  in  astigmatism  "against  the  rule,"  the 
instrument's  readings  are  .50  D.  to  1  D.  less  than  they  should  be. 

SYMMETRIC    ASTIGMATISM    WITH    THE    RULE 

This  case  then  is  one  of  symmetric  astigmatism  with  the  rule. 
We  call  it  symmetric,  because  the  axis  of  right  cylinder  is  just  as 
far  to  the  right  of  the  median  line  as  the  axis  of  the  left  cylinder  is 
to  the  left ;  or  in  other  words,  the  combined  value  of  the  two  meri- 
dians equals  1800.  We  call  it  "  with  the  rule, "because  the  excess 
of  curvature  is  vertically. 

Perhaps  the  question  may  occur  to  some  of  you  as  to  why  the 
mires  in  this  case  have  overlapped  as  we  turn  the  telescope  from 


A  Case  of  Astigmatism  119 

the  primary  to  the  secondary  position.  It  is  simply  because  of  the 
increased  curvature  in  the  vertical  meridian,  or  rather  of  the  les- 
sened radius  of  the  curvature,  which  crowds  the  doubled  images  of 
the  mires  into  less  space,  which  can  be  accomplished  only  by  over- 
lapping at  their  inner  edges. 

Now,  with  this  definite  information  gained  from  the  ophthal- 
mometer, the  trial  case  examination  is  much  more  simplified.  We 
no  longer  have  to  try  one  lens  after  another  to  the  weariness  of  the 
patient  and  the  tiring  of  her  eyes,  but  we  have  quickly  determined 
by  an  objective  method  the  condition  of  refraction,  which  we  can 
verify  or  disprove  by  the  subjective  method  without  the  trying  on 
of  innumerable  lenses. 

I  place  a  +  4  D.  cylinder  in  the  trial  frame  over  the  right  eye 
with  the  axis  at  no°.  This  at  once  causes  a  marked  improvement 
in  vision,  and  enables  the  patient  to  read  the  No.  30  line.  I  rotate 
the  cylinder  first  one  way  and  then  the  other,  with  the  effect  of 
producing  great  impairment  of  vision.  Our  patient  without  any 
hesitation  decides  on  no0  as  the  best  position  for  the  axis  of  the 
cylinder. 

I  hold  a  -f-  .50  D.  and  a  +  1  D.  sphere  in  front  of  this  cylin- 
der, both  of  which  spheres  are  promptly  rejected.  I  place  a  + 
.50  D.  cylinder  over  it  with  axis  in  same  position,  which  our  patient 
hardly  knows  whether  to  accept  or  reject,  but  finally  decides  it  is 
better  without. 

I  then  try  a  —  .  50  D.  cylinder  with  axis  at  right  angles,  which 
is  at  once  accepted  and  raises  vision  to  f  %.  I  rotate  the  concave 
cylinder  so  that  its  axis  coincides  with  that  of  the  convex  cylinder, 
and  this  position  is  not  as  good  as  when  their  axes  are  at  right 
angles. 

I  make  my  test  of  the  left  eye  in  the  same  way,  using 
the  strength  of  cylinder  and  the  position  of  axis  indicated  by 
the  ophthalmometer,  and  after  one  or  two  trials,  I  quickly  find 
the  correcting  lens,  and  am  now  in  position  to  prescribe  as 
follows  : 

O.  D.,  —  .50  S.  O  +  4.50  D.  cyl.  axis  no° 
O.  S.,  +  4.50  D.  cyl.  axis  700 

which  lenses  as  a  matter  of  course  must  be  worn  constantly. 

This  is  really  a  difficult  case,  especially  so  for  a  man  who 
depends  upon  his  trial  lenses,  for  the  reason  that  the  weaker  lenses 


120  Clinics  in  Optometry 

with  which  it  is  customary  to  commence  our  examination,  are  so 
far  from  the  proper  correction  that  they  produce  but  little  effect  on 
vision,  and  the  examiner  gropes  around  in  the  dark  trying  aimlessly 
spheres  and  cylinders,  convex  and  concave,  with  no  result  at  all  or 
most  likely  an  incorrect  prescription. 

IMPORTANCE    OF    THE    OPHTHALMOMETER 

How  different  in  this  case  ;  before  we  try  any  test  lenses  at  all, 
we  use  the  ophthalmometer,  and  this  at  once  indicates  the  character 
and  extent  of  the  error,  and  points  out  the  lens  to  be  used  and  how 
it  should  be  placed  before  the  eye. 

Perhaps  every  case  may  not  be  so  clear  and  positive  as  this 
one,  but  let  me  give  you  a  few  general  directions  for  putting  glasses 
in  the  trial  frame  after  the  ophthalmometer  indicates  astigmatism 
with  the  rule  as  in  this  case. 

ist.  Try  convex  cylinders  alone,  placing  the  axis  in  the  posi- 
tion indicated  by  the  instrument  and  about  .50  D.  weaker  than  the 
overlapping  calls  for.  Increase  strength  of  cylinder  as  long  as 
patient  accepts,  or  decrease  slightly  if  necessary.  Rotate  cylinder 
slowly  both  to  right  and  left,  in  order  to  be  sure  that  you  have  the 
correct  position  for  the  axis. 

2d.  After  having  determined  the  convex  cylinder  that  affords 
best  vision,  try  convex  spheres  in  front  of  it,  making  the  effort  to 
have  them  accepted. 

3d.  In  case  the  vision  is  not  made  perfect  by  the  convex 
cylinder  or  sphero-cylinder,  try  concave  cylindrical  lenses  with 
axis  at  right  angles,  cammencing  with  —  .  25  D.  and  gradually  and 
slowly  increasing  same  until  normal  vision  is  reached. 

This  would  be  particularly  indicated  if  in  a  case  like  this  one 
under  consideration,  where  the  mires  overlapped  5  D.,  and  the 
patient  would  accept  only  -f  2  D.  cylinder  axis  900  with  improve- 
ment in  vision,  all  additional  convex  cylinders  and  convex  spheres 
being  rejected,  we  would  at  once  suspect  mixed  astigmatism  and 
proceed  to  try  concave  cylinders  with  axis  at  right  angles  to  the 
convex  cylinders. 

4th.  If  convex  cylinders  are  positively  rejected,  then  concave 
cylinders  with  axis  in  same  meridian  as  the  primary  position. 

5th.  If  such  concave  cylinders  fail  to  raise  acuteness  of  vision 
to  normal,  then  the  cautious  addition  of  concave  spheres. 


A  Case  of  Astigmatism  121 

I  would  suggest  to  you  the  following  routine  of  examination  : 

1  st.  Ascertain  acuteness  of  vision. 

2d.  Measure  amplitude  of  accommodation. 

3d.  Use  of  ophthalmometer. 

4th.  Trial  case  examination. 

5th.  Muscle  tests. 

6th.  Ophthalmoscope. 

7th.  Retinoscope. 

If  I  have  impressed  upon  you  the  great  assistance  offered  by 
the  ophthalmometer  in  the  early  stages  of  an  examination,  as  dem- 
onstrated by  this  case,  I  have  succeeded  in  my  purpose  to-day  ; 
and  as  our  time  is  exhausted,  I  will  not  detain  you  further  to  com- 
plete the  remaining  steps  of  the  examination. 


A    Case     of     Hypermetropia,     Illustrating    the    Fogging 
Method 

[Clinic  No.  20] 

J.  A.  H. ,  twenty-five  years  of  age,  machinist  by  occupation, 
complains  principally  of  headaches. 

We  find  the  acuteness  of  vision  even  better  than  normal,  as  the 
patient  can  name  at  least  half  the  letters  on  the  No.  15  line.  This 
practically  excludes  astigmatism  ;  and,  of  course,  myopia  is  not  to 
be  thought  of. 

But  in  accordance  with  the  routine  method  of  examination 
which  I  advised  at  our  last  clinic,  we  will  first  make  use  of  the 
ophthalmometer,  which  shows  a  slight  overlapping  in  the  vertical 
meridian.  As  this  is  the  normal  condition  of  the  cornea,  that  is, 
as  the  curvature  of  the  vertical  meridian  is  usually  a  little  shorter 
than  the  horizontal,  we  may  assume  in  this  case,  at  least  as  far  as 
the  cornea  indicates,  that  astigmatism  is  absent. 

We  now  ask  our  patient  to  return  to  the  chair  facing  the  test 
cards  in  order  that  we  may  make  a  trial  case  examination. 

We  have  excluded  myopia  and  astigmatism,  and  therefore  we 
have  no  use  in  this  case  for  concave  lenses  or  cylinders.  The 
visual  acuity  not  being  below  the  standard,  the  refraction  must  be 
either  emmetropic  or  hypermetropic,  and  in  order  to  determine 
this  question  quickly,  we  place  a  pair  of  +  1  D.  spheres  before  the 
eyes,  asking  the  patient  if  he  can  still  see  the  same  line.  He 
replies  that  he  can  and  names  the  same  letters  he  saw  before. 
Therefore  this  case  is  proven  to  be  one  of  hypermetropia  by  the 
acceptance  of  these  convex  lenses  ;  and  it  only  remains  for  us  to 
measure  the  amount  and  to  test  each  eye  separately. 

THE    FOGGING   SYSTEM 

As  several  members  of  the  class  have  asked  me  about  the 
"logging  system,"  and  expressed  a  desire  for  instruction  in  its  use, 
I  will  embrace  this  opportunity  to  demonstrate  it. 

And,  first,  what  is  the  fogging  system  ?  Many  students  seem 
to  have  a  hazy  idea  of  it,  while  other  practitioners  of  optometry  who 
perhaps  have  some  knowledge  of  the  method,  do  not  appreciate  its 

122 


A  Case  of  Hypermetropic*,  123 

full  value  ;  so  that  between  ignorance  and  undervaluation  of  the 
fogging  system,  it  is  probably  not  used  nearly  as  much  as  it 
should  be. 

The  fogging  system  is  a  subjective  method  of  determining  the 
full  amount  of  hypermetropia  in  an  eye  under  examination,  by  an 
endeavor  to  produce  a  relaxation  of  the  accommodation,  which  is 
concealing  a  certain  amount  of  latent  defect. 

Latent  hypermetropia  is  the  bugbear  of  the  refractionist,  and 
in  the  endeavor  to  uncover  it,  the  optometrist  makes  use  of  the 
fogging  system,  while  the  oculist  falls  back  on  a  cycloplegic. 
The  advantages  and  disadvantages  of  ' '  drops  ' '  have  been  bitterly 
argued  by  medical  and  non-medical  refractionists,  and  we  will 
not  attempt  to  decide  which  side  is  right,  but  I  want  to  thor- 
oughly instruct  you  in  this  method,  which  in  so  many  cases 
detects  the  latent  defect  and  renders  the  use  of  atropine  but 
seldom  necessary. 

In  a  hypermetropic  eye  as  soon  as  opened,  the  accommodation 
instinctively  comes  into  action  in  order  to  afford  perfect  vision, 
which  is  accomplished  by  an  increase  in  the  refractive  power  of 
the  eye.  This  being  continued  year  in  and  year  out  becomes  a 
fixed  habit  which  is  not  easily  abandoned. 

We  wish  to  supplant  the  insufficient  refraction,  or  in  other 
words  correct  the  hypermetropia,  by  means  of  convex  lenses. 
In  order  to  allow  us  to  do  this,  the  ciliary  muscle  must  retire  from 
the  field  of  action  ;  but  on  account  of  its  fixed  habit  of  contraction, 
this  is  impossible  for  it  to  do  at  once.  Therefore  the  convex  lens 
is  rejected,  because  it  in  connection  with  the  active  accommodation, 
produces  an  excess  of  refractive  power  and  a  consequent  blurring 
of  vision. 

We  overwhelm  and  disconcert  the  accommodation  by  means 
of  a  strong  convex  lens.  The  strength  of  the  lens  needed 
will  vary  in  different  cases,  but  it  should  be  strong  enough  to 
make  the  large  letter  E  (marked  No.  200)  barely  discernible, 
so  that  the  patient  is  in  doubt  whether  it  is  an  E  or  an  F  or  a 
B  or  an  H. 

The  optometrist  should  then  busy  himself  with  some  little 
matter  at  his  desk,  while  the  patient  is  instructed  to  quietly  look  at 
the  letter  for  a  few  minutes  in  an  effort  to  determine  exactly  what  it 
is.  In  most  cases  the  letter  gradually  becomes  entirely  legible, 
and  he  can    perhaps  even    make   a   guess   at   the   two   letters  on 


124  Clinics  in  Optometry 

the    ioo  line.       This    proves    that    there    has    been    some   relaxa- 
tion of  the  accommodation. 

EFFECT    OF    A    STRONG    CONVEX    LENS 

You  will  understand  that  when  a  strong  convex  lens  is  placed 
before  the  eye,  its  refractive  power  is  greatly  increased,  the  rays 
of  light  are  brought  to  a  focus  in  front  of  the  retina  and  a  condition 
of  artificial  myopia  produced.  Any  contraction  of  the  accommo- 
dation under  such  conditions  only  makes  vision  worse  ;  while  any 
relaxation  would  afford  an  improvement  in  vision.  This  furnishes 
an  incentive  to  relaxation,  as  the  natural  instinct  is  for  clear  vision, 
and  in  this  way  with  a  little  patience,  some  lessening  of  the  ciliary 
contraction  may  be  expected  to  occur.  The  strength  of  the  convex 
lens  may  now  be  gradually  decreased  until  the  patient's  vision  is 
raised  to  f  $.  By  this  method  we  have  tempted  the  accommodation 
to  relax,  or  we  might  say  we  have  caught  it  off  its  guard  and 
captured  a  large  part,  if  not  all  the  hypermetropia. 

Now  a  little  attention  as  to  the  details  of  the  procedure.  In 
the  first  place,  instead  of  an  opaque  disk  before  the  eye  not  under 
examination,  place  an  exceedingly  strong  convex  lens,  which 
while  affording  no  real  vision  of  the  letters,  at  least  allows  the 
blurred  effect  of  the  light  and  card  being  seen  at  the  usual  distance 
of  twenty  feet,  thus  favoring  a  relaxation  of  the  accommodation 
much  more  than  an  opaque  disk  would  do. 

In  the  second  place,  do  not  reduce  the  convexity  before  the 
eye  by  substituting  weaker  convex  lenses  one  after  the  other. 
Perhaps  you  have  started  with  -f-  5  D. ,  and  after  allowing  a  few 
minutes  for  the  eye  to  adapt  itself,  you  have  replaced  it  with  a 
-J-  4.50  D. ,  which  again  you  have  replaced  with  a  -\~  4  D. ,  and  so 
on  until  you  have  reached  a  lens  that  permits  of  the  normal  visual 
acuity. 

If  this  has  been  your  idea  of  the  proper  procedure  in  the 
fogging  system,  you  have  been  on  the  wrong  track,  as  this  is  not 
the  correct  manner  of  reducing  the  strong  convex  lenses.  Let  us 
consider  this  matter  in  detail. 

You  start  with  a  +  5  D.  lens  with  which  you  expect  to  coax  a 
relaxation  of  the  ciliary  muscle.  Then  you  remove  it  and  replace 
it  with  a  -j-  4.50  D.  Now  what  have  you  done?  As  soon  as  the 
-f  5  D.  is  removed,  all  restraining  influence  upon  the  accommodation 
is  taken  away  and   is  stimulated  into  action  again  to  focus   the 


A  Case  of  Hypermetropia  125 

letters  upon  the  retina.  Then  you  put  on  the  +  4-5°  D.  f°r  the 
purpose  of  restraining  the  accommodation  ;  then  you  remove  it 
and  again  give  the  accommodation  full  swing.  Thus  you  alternate 
from  +  5  D.  to  nothing,  then  to  +  4.50  D.,  then  to  nothing,  then 
to  +  4  D. ,  again  to  nothing,  and  so  on.  Can  you  expect  to  restrain 
and  relax  the  accommodation  in  this  way  ?  Are  you  not  rather 
stimulating  it  into  activity  ?  You  aggravate  the  very  condition  you 
are  endeavoring  to  modify  by  such  a  method  of  procedure  ;  and 
you  get  no  better  results,  if  as  good,  as  the  usual  method  of  com- 
mencing with  the  weak  convexes  and  gradually  increasing  their 
strength. 

THE    PROPER    PROCEDURE 

Perhaps  you  are  commencing  to  ask  how  you  shall  proceed, 
and  I  am  glad  to  be  able  to  instruct  you  in  the  proper  way.  After 
you  have  placed  the  -f-  5  D.  before  the  eye,  leave  it  there  ;  do  not 
remove  it  for  any  purpose,  but  instead  get  the  effect  of  +  4. 50  D. 
by  placing  —  .  50  D.  in  front  of  it.  Then  increase  this  latter  lens 
to  —  1  D.,  then  to  —  1.50  D.  and  so  on  as  necessary.  In  this 
way  the  restraining  influence  of  the  original  convex  lens  is 
constantly  before  the  eye,  and  no  opportunity  is  afforded  for 
stimulation  of  the  accommodation,  but  on  the  other  hand  every 
inducement  for  it  to  become  passive. 

The  concave  lens  is  increased  until  normal  vision  is  afforded, 
and  the  difference  between  the  two  lenses  will  represent  the  amount 
of  error  that  has  been  uncovered.  You  can  readily  see  that  this  is 
the  only  proper  way  to  employ  the  fogging  system  in  order  to  gain 
its  advantages.  In  fact,  it  is  not  fair  to  apply  this  term  to  the 
method  first  described.  Therefore,  if  some  of  you  have  failed  to 
get  satisfactory  results  from  the  fogging  system,  you  should  not 
condemn  the  method  itself,  but  rather  carefully  scrutinize  your 
manner  of  conducting  it  to  see  if  you  have  been  sufficiently  careful, 
accurate  and  painstaking. 

We  will  now  make  use  of  the  fogging  method  in  the  case 
before  us.  We  want  to  reduce  his  vision  to  yVtf  scant-  We  place 
this  +  6  D.  before  the  right  eye  and  a  -f  10  D.  before  the  left. 
These  lenses  fog  his  vision  to  such  an  extent  that  he  says  he  can 
barely  distinguish  the  card  much  less  any  letters  upon  it.  We 
therefore  replace  the  +  6  D.  with  a  +  5  D.  over  the  right  eye,  and 
now  he  tells  us  he  can  make  out  the  form  of  the  large  letter  at  the 
top  but  he  cannot  name  it.     We  ask  him  to  look  at  it  quietly  for  a 


126  Cli?iics  in  Optometry 

moment  or  two  while  we  make  the  entries  of  his  case  in  our  record 
book.  When  we  return  he  tells  us  the  letter  is  an  E  although  he 
says  it  is  not  sharp  and  distinct.  We  have  thus  secured  a  slight 
relaxation  of  the  accommodation  and  placed  the  eye  in  a  favorable 
position  for  further  examination. 

This  eye  is  to  all  intents  and  purposes,  for  the  time  being  at 
least,  myopic,  and  keeping  this  fact  in  mind  we  proceed  with  the 
test  lenses  as  we  would  in  any  other  case  of  myopia.  Where  a 
case  is  already  myopic  the  fogging  system  is  not  applicable,  but  it 
is  only  of  value  in  estimating  the  refraction  of  an  eye  that  has 
some  form  of  hypermetropia,  either  simple  hypermetropia  or 
hypermetropic  astigmatism. 

We  place  a  —  ,50  D.  in  front  of  the  convex  lenses  ;  this 
improves  vision,  makes  the  E  distinct  and  brings  out  the  letters  on 
the  next  line.  We  increase  to  —  1  D.  and  then  to  —  1.50  D., 
each  change  affording  a  still  further  improvement  in  vision,  until 
now  the  patient  can  with  difficulty  discern  some  of  the  letters  on 
the  No.  30  line.  Now  we  must  increase  more  gradually,  and  we 
try  a  —  1.75  D.  next.  This  makes  the  No.  30  line  clear  and 
brings  out  some  of  the  letters  on  the  No.  20  line.  We  now 
advance  to  —  2D.,  with  which  vision  is  \%  clearly,  and  a  few 
letters  on  the  No.   15  line  can  be  guessed  at. 

Now  what  have  we  in  the  trial  frame  ?  A  -f  5  D.  and  a  —  2  D. , 
which  by  algebraic  addition  equals  +  3  D.,  and  this  represents  the 
amount  of  hypermetropia  present.  We  examine  the  left  eye  in  the 
same  way,  and  find  an  equal  amount  of  defect. 

We  have  then  in  this  case  uncovered  3  D.  of  the  hyper- 
metropia, which  the  ciliary  muscle  is  constantly  overcoming.  For 
all  practical  purposes  this  represents  the  total  hypermetropia, 
although  it  is  barely  possible  that  a  strong  cycloplegic  might  show 
a  slight  increase.  But  the  measurement  of  the  amount  of  hyper- 
metropia and  the  proper  glass  to  prescribe  are  two  different 
matters.  I  do  not  think  it  wise  in  this  case  to  attempt  to  correct 
the  total  amount  of  error. 

LET   JUDGMENT    AND    CIRCUMSTANCES    DECIDE 

There  is  no  hard  and  fast  rule  as  to  just  how  much  should  be 
deducted,  and  authorities  do  not  agree  on  this  point.  We  must 
be  guided  by  the  circumstances  of  each  case,  the  age,  occupation, 
whether  glasses  have  previously  been  worn,  and  the  condition  of 


A  Case  of  Hypermetropia  1 27 

the  muscle  balance.  When  esophoria  is  present,  we  would  be 
justified  in  prescribing  nearly  the  full  correction  ;  while  in  the 
presence  of  exophoria,  we  would  make  a  liberal  reduction  from  the 
total  error,  for  the  following  reasons  :  in  esophoria  the  stronger  the 
convex  lens,  the  less  the  esophoria,  and  we  more  nearly  approach 
the  normal  relation_that  should  exist  between  the_  accommodation 
and  convergence.  While  in  _exoghqrfa, _..the  stronger  convex_lens 
increases  the  divergence  oj  the  visual  axes,  and  hence  we  give 
preference  to  the  weaker  lens  in  order  to  lessen  the  disparity 
between  accommodation  and  convergence. 

Therefore,  before  deciding  on  the  glasses  to  be  prescribed,  we 
will  inquire  into  the  muscular  equilibrium.  We  will  make  use  of 
the  Maddox  rod,  which  is  the  most  satisfactory  all-around  muscle 
test.  The  rod  is  placed  over  the  left  eye  and  the  patient's  attention 
directed  to  the  light  across  the  room.  In  answer  to  our  inquiry  as 
to  the  position  of  the  red  streak,  the  gentleman  tells  us  it  is  to  the 
left.  This  is  a  condition  of  homonymous  diplopia,  which  we  know 
must  be  due  to  an  inward  turning  of  the  eyesL  in  other  words,  to 
esophoria  ;  the  amount  of  which  is  measured  by  the  strength  of 
prism  base  out  that  is  required  to  bring  the  streak  back  to  the 
light.  After  trial  of  a  few  prisms  we  find  that  8°  is  the  measure  of 
the  esophoria. 

We  are  now  in  position  to  determine  the  lenses  to  be 
prescribed.  Even  in  view  of  the  decided  amount  of  esophoria,  we 
hardly  feel  justified  in  attempting  to  correct  the  amount  of  error, 
and  especially  as  the  young  man  has  never  worn  glasses  before  ; 
but  on  the  other  hand  the  esophoria  that  is  present  indicates  that 
the  glasses  should  not  be  too  weak,  and  therefore  taking  all  the 
circumstances  of  the  case  into  consideration,  we  will  order  -j-  2.50 
D. ,  which  we  will  advise  to  be  worn  constantly.  These  glasses 
will  probably  seem  somewhat  annoying  at  first,  and  we  will  prepare 
our  patient  by  telling  him  that  they  may  cause  the  ground  to  appear 
to  slant,  and  that  he  may  see  somewhat  better  without  them,  but 
that  he  should  persevere  in  their  use,  and  in  a  week  or  two  they 
will  be  entirely  satisfactory. 


Astigmatism  With  the  Rule 


[Clinic  No.  21] 

Miss  Carrie  B.,  aged  twenty-one,  complains  of  headaches. 

We  notice  she  is  wearing  glasses  at  present,  and  in  answer  to 
our  inquiry  she  tells  us  she  has  had  them  for  the  past  four  years. 
We  ask  her  to  let  us  see  the  glasses,  and  we  find  they  are  both 
—  .75  D.  cyl.  axis  1800. 

The  first  step  in  the  examination  of  this  case  (as  of  every  case 
of  refractive  error)  is  to  ascertain  the  acuteness  of  vision,  which  we 
find  to  be  f£  in  each  eye.  We  next  find  the  range  of  accommoda- 
tion with  each  eye  without  glasses  to  be  from  5"  to  11",  reading 
the  .50  D.  type. 

Following  the  routine  method  of  examination  we  have  advised 
you  to  pursue,  we  now  turn  to  the  ophthalmometer  to  determine 
the  presence  or  absence  of  astigmatism. 

Examining  the  right  eye,  first  we  focus  the  instrument  so  that 
we  obtain  a  clear  image  of  the  mires,  and  then  we  revolve  the  tube 
to  find  in  which  position  the  long  meridian  lines  are  straight  and 
unbroken,  which  is  exactly  in  the  horizontal  meridian,  and  here  we 
find  the  curvature  of  the  cornea  has  a  value  of  45  D.  Turning  the 
tube  a  quarter  of  a  circle,  we  obtain  a  reading  of  47.50  D.  in  the 
vertical  meridian.  We  examine  the  other  eye  with  exactly  the 
same  result. 

This,  then,  is  a  case  of  astigmatism  "  with  the  rule,"  the  verti- 
cal meridian  exceeding  the  horizontal  meridian  by  2.50  D. 

EXPLANATION    OF    ASTIGMATISM 

I  have  found  so  much  confusion  in  the  minds  of  my  younger 
students,  and  I  may  say  also  even  in  the  minds  of  optometrists  of 
considerable  experience,  about  astigmatism  with  the  rule  and  astig- 
matism against  the  rule,  that  I  will  give  you  a  short  and  explicit 
description  of  the  former  as  exemplified  in  the  case  before  us. 

You  will  remember  in  our  studies  of  the  anatomy  of  the 
eye,  we  found  that  the  curvature  of  the  anterior  surface  of 
the  cornea  did  not  accurately  correspond  to  a  section  of  a  sphere, 
but    that    the    vertical    meridian    was    slightly    sharper    than  the 


Astigmatism   With  the  Rule  129 

horizontal  ;  this  is  the  condition  that  is  found  in  the  large  majority 
of  all  eyes. 

Now,  then,  when  we  have  a  case  of  astigmatism  in  which  the 
vertical  meridian,  or  a  meridian  on  either  side  of  the  vertical  that 
is  within  45  °  of  it,  is  more  sharply  curved  than  the  meridian  at 
right  angles  to  it,  we  classify  the  case  as  one  of  ' '  astigmatism  with 
the  rule. ' ' 

This  simply  means  that  the  vertical  meridian,  or  a  meridian 
near  to  it,  presents  the  sharpest  curve  and  possesses  the  greater 
refractive  power,  and  thus  corresponds  to  the  usual  normal  condi- 
tion of  the  average  pair  of  eyes.  For  this  reason  it  is  said  to  be 
according  to  the  rule,  or  with  the  rule.  French  writers  sometimes 
call  this  "direct"  astigmatism,  in  contrast  to  astigmatism  against 
the  rule,  which  they  designate  as  "indirect"  astigmatism.  Now, 
gentlemen,  this  is  the  whole  meaning  of  astigmatism  with  the  rule, 
and  this  is  all  there  is  to  it. 

Sometimes  beginners  in  optometry  ask  me  if  hypermetropic 
astigmatism  is  not  always  with  the  rule,  and  if  myopic  astigmatism 
is  not  always  against  the  rule.  This  question  occurs  to  them 
because  they  know  that  hypermetropic  astigmatism  is  usually  cor- 
rected by  a  convex  cylinder  with  axis  at  900,  and  myopic  astigma- 
tism by  a  concave  cylinder  with  axis  at  1800.  The  fact  of  the 
matter  is  that  the  hypermetropic  and  myopic  astigmatism  above 
mentioned  are  both  with  the  rule,  and  it  makes  no  difference 
whether  the  astigmatism  be  hypermetropic  or  myopic,  whether  it 
be  simple,  compound  or  mixed,  so  long  as  the  vertical  meridian,  or 
one  adjacent  to  it,  has  a  sharper  curvature  than  the  one  at  right 
angles  to  it. 

In  order  to  make  this  perfectly  clear,  so  that  no  member  of  the 

class  can  go  astray  on  this  point,  I  will  make  a  diagram  on   the 

blackboard  to  illustrare  the  shape  of  the  cornea  in  astigmatism  with 

the  rule  : 

Vert. 


Hor.  J 1800 


130  Clinics  in  Optometry 

You  will  see  by  this  diagram  that  the  vertical  or  90th  meridian 
is  shorter  than  the  horizontal  or  180th  meridian.  Or,  in  other 
words,  the  vertical  meridian  has  a  sharper  curvature,  while  the 
horizontal  meridian  is  flatter.  Therefore,  the  vertical  meridian  has 
a  greater  refractive  power  than  the  horizontal,  and  the  focus  of  the 
vertical  meridian  is  always  in  front  of  the  focus  of  the  horizontal 
meridian. 

SIMPLE    HYPERMETROPIC    ASTIGMATISM 

\x\_simplc  hypermetropic  astigmatism  with  the  rule,  the  verti- 
cal meridian  is  emmetropic  and  the  horizontal  meridian  hyperme- 
tropic. Let  me  call  your  attention  to  the  fact  that  the  refraction  of 
the  vertical  meridian  is  not  absolutely  increased,  but  only  relatively 
so,  as  compared  with  the  horizontal,  which  is  flatter  than  normal  ; 
but  still,  this  corresponds  to  our  definition  of  astigmatism  with  the 
rule,  which  was  that  the  vertical  meridian  exceeds  the  horizontal  in 
curvature.  We  correct  this  form  of  astigmatism  by  a  convex  cylin- 
der with  axis  at  900,  the  rationale  of  which  is  as  follows  :  the  axis 
of  the  cylinder  being  plane,  leaves  the  vertical  or  emmetropic  meri- 
dian unaffected  ;  while  the  horizontal  meridian  of  the  cylinder  in 
which  its  positive  refracting  power  lies,  supplements  or  increases 
the  flat  or  hypermetropic  meridian  of  the  eye  and  builds  it  up  to 
normal,  so  as  to  equalize  the  refraction  of  the  two  meridians  and 
thus  correct  the  astigmatism. 

In  si?npie^myopjc_astigmatisni_vath.  the  rule,  the  emmetropic 
meridian  is  now  horizontal,  while  the  vertical  meridian  i_s_  myopic. 
In  this  case,  the  refraction  of  the  vertical  meridian  is  not  only  rela- 
tively but  absolutely  greater  than  the  horizontal,  and  you  have  no 
difficulty  in  understanding  that  this  condition  corresponds  to  our 
definition  of  astigmatism  with  the  rule. 

We  correct  this  form  of  astigmatism  by  a  concave  cylinder 
with  axis  at  1800,  the  principle  of  which  is  as  follows  :  the  axis  of 
the  cylinder  being  plane  leaves  the  horizontal  or  emmetropic  meri- 
dian unaffected,  while  the  veritcal  meridian  of  the  cylinder  in  which 
its  diminishing  refractive  power  lies,  neutralizes  or  reduces  the 
excessive  refractive  power  of  the  vertical  or  myopic  meridian,  and 
makes  it  the  same  as  the  horizontal  meridian,  thus  equalizing  the 
two  meridians  and  thus  correcting  the  astigmatism. 

In  cqnifiouiid  hyfrcrmchofiic  astigmatism  with  the  rule,  both 
meridians" are  flatter  than  normal  and_both  focus  bark"  01  the  retina, 
but  the  horizontal  is  the  flatter  of  the  two  and  its  focus  is  farther 


Astigmatism  With  the  Ride  131 

away  from  the  retina  than  is  that  of  the  vertical  meridian.  The 
refraction  of  the  vertical  meridian  is  therefore  greater  than  the  hori- 
zontal, thus  corresponding  to  our  definition  of  astigmatism  with 
the  rule. 

In  compound  myopic  astigmatism  with  the  rule,  both  meridians 
have  a  sharper  curvature  than  normal  and  both  focus  in  front  of  the 
retina,  but  the  vertical  meridian  has  the  more  pronounced  curve 
and  its  focus  is  farther  in  front  of  the  retina  than  is  that  of  the  hori- 
zontal meridian.  The  refraction  of  the  vertical  meridian  is  obvi- 
ously greater  than  the  horizontal,  and  thus  without  the  need  of  any 
reasoning  is  classed  as  astigmatism  with  the  rule. 

MIXED    ASTIGMATISM    WITH    THE    RULE 

In  mixed  astigmatism  with  the  rule,  the  conditions  are  a  little 
more  complicated  and  perhaps  not  quite  so  quickly  grasped.  The 
vertical  meridian  is  more  curved  than  normal  (myopic),  and  its 
focus  is  in  front  of  the  retina.  The  horizontal  meridian  is  flatter 
than  normal  (hypermetropic),  and  its  focus  is  behind  the  retina. 
As  neither  meridian  focuses  on  the  retina  it  cannot  be  simple  astig- 
matism ;  but  as  one  is  in  front  and  the  other  back  of  the  retina,  it 
is  mixed  astigmatism  ;  and  as  the  vertical  meridian  dominates  the 
horizontal  in  refractive  power,  it  corresponds  to  our  definition  of 
astigmatism  with  the  rule. 

The  correction  of  this  form  of  astigmatism  calls  for  both  a  con- 
vex and  a  concave  cylinder.  The  convex  cylinder  is  placed  with 
axis  at  900,  thus  building  up  the  refraction  of  the  horizontal  meri- 
dian to  the  normal  standard,  and  leaving  the  vertical  meridian 
undisturbed.  The  concave  cylinder  is  placed  with  axis  at  1800, 
thus  reducing  the  excessive  refraction  of  the  vertical  meridian  to  the 
normal  standard,  and  leaving  the  horizontal  meridian  undisturbed. 
By  thus  increasing  the  horizontal  and  diminishing  the  vertical,  the 
two  meridians  are  equalized,  and  the  astigmatism  thus  corrected. 

I  have  shown  you  by  referring  to  the  five  forms  of  regular 
astigmatism,  that  it  may  be  with  the  rule  in  any  or  all  of  its  forms  ; 
the  one  thing  necessary  to  make  it  such  is  that  the  curvature  of  the 
vertical  meridian,  or  adjacent  to  it,  shall  be  sharper  than  the  hori- 
zontal or  the  meridian  at  right  angles  to  it. 

I  trust  I  have  succeeded  in  making  clear  to  you  the  meaning 
of  astigmatism  with  the  rule  ;  and  we  will  now  proceed  with  the 
examination  of  our  patient.     You  will  remember  that  we  found  a 


132  Clinics  in  Optometry 

corneal  astigmatism  with  the  rule  of  2.50  D.  In  one  of  our  former 
clinics  I  told  you  in  this  form  of  astigmatism  we  must  deduct  .50 
D.  from  the  reading  of  the  instrument,  and  explained  to  you  the 
reason  why  ;  we  follow  this  rule,  and  now  we  have  2  D.  of  astig- 
matism to  be  accounted  for. 

We  commence  with  a  .50  D.  cylinder,  and  for  reasons  with 
which  you  are  all  now  familiar,  we  select  a  convex  and  place  its 
axis  at  900.  This  is  accepted,  as  are  also  successively  a  -j-  .75  D. 
cyl.  and  a  -f-  1  D.  cyl. ,  axis  900,  each  in  turn  affording  a  still 
greater  improvement  in  vision.  The  next  stronger  lens,  -f-  1.25  D. 
cyl.  axis  900,  was  rejected  as  not  being  as  good  as  the  former  lens. 

With  this  +  1  cyl.,  vision  has  been  raised  to  f$  clearly.  We 
have  reached  the  limit  of  acceptance  of  convex  cylinders,  but  we 
have  not  yet  raised  the  vision  to  normal,  nor  have  we  accounted  for 
the  2  D.  of  astigmatism  indicated  by  the  ophthalmometer.  This 
causes  us  to  suspect  mixed  astigmatism,  and  we  try  a  —  .25  D.  cyl. 
with  axis  at  right  angles  to  the  convex  cylinder. 

This  improves  vision  :  we  rotate  it  to  900,  where  it  is  rejected, 
and  then  back  again  to  1800,  where  it  is  very  much  better.  This 
proves  that  our  suspicion  of  mixed  astigmatism  is  correct,  and  we 
cautiously  increase  the  concave  cylinder  .25  D.  at  a  time,  each 
increase  affording  a  still  greater  improvement  in  vision  until  we 
reach  —  1  D.  cyl.  axis  1800,  with  which  vision  equals  \%  clearly, 
and  the  ophthalmometry  estimate  of  the  astigmatism  is  all 
ccounted  for. 

The  left  eye  is  examined  in  the  same  way  with  exactly  the 
came  results. 

In  this  case  the  horizontal  meridian  shows  a  deficiency  of 
refractive  power,  which  is  corrected  by  the  convex  cylinder  with 
axis  at  900,  while  the  vertical  meridian  shows  an  excess  of  refractive 
power  which  is  corrected  by  the  concave  cylinder  with  axis  at  1800. 
The  refraction  of  the  horizontal  meridian  is  increased,  and  that  of 
the  vertical  meridian  diminished,  and  thus  the  two  meridians  are 
equalized,  and  the  astigmatism  neutralized. 

COMMON    ERROR    OF    REFRACTIONISTS 

It  might  be  profitable  for  you  to  consider  for  a  moment  the 
error  that  was  made  by  the  refractionist  who  fitted  this  lady's  first 
glasses,  which,  as  I  told  you,  are  —  .75  D.  cyl.  axis  1800.  I  have 
seen  many  cases  of  astigmatism  where  the  cylinders  prescribed  were 


Astigmatism  With  the  Rule  133 

concave  when  they  should  have  been  convex.  This  error  is  so 
common,  so  apt  to  cause  eyestrain  instead  of  relief,  and  is  so  inex- 
cusable on  the  part  of  an  educated  optometrist,  that  I  made  it  the 
subject  of  one  of  our  clinics  (No.  3),  in  order  to  impress  it  upon 
our  minds,  and  so  that  no  member  of  this  class  would  have  excuse 
for  such  a  lapsus. 

In  this  case  the  myopic  meridian  is  cared  for,  while  the  hyper- 
metropic meridian  is  disregarded.  The  patient  would  have  received 
more  relief  if  these  conditions  had  been  reversed,  because  it  is  the 
effort  on  the  part  of  the  patient  to  overcome  the  hypermetropic 
meridian  (not  the  myopic)  that  causes  the  strain. 

This  patient's  distant  vision  is  poor  and  she  holds  her  book 
close,  it  is  true  ;  but  in  spite  of  this  you  must  not  jump  at  the  con- 
clusion that  the  defect  is  entirely  myopic.  Follow  the  rule  I  have 
so  often  repeated,  to  begin  the  test  with  convex  lenses,  either 
spheres  or  cylinders,  allowing  the  ciliary  muscle  a  moment's  time  to 
accept  the  -f-  lenses,  and  do  not  hastily  turn  to  concaves,  not  at 
least  until  you  have  used  reasonable  efforts  to  have  the  convexes 
accepted. 


Astigmatism  Against  the  Rule 


[Clinic  No.  22] 

J.  R.  S.,  aged  thirty-three  years,  complains  of  occipital  pain 
and  says  his  eyes  get  heavy  unless  he  wears  his  glasses.  Tells  us 
he  has  been  wearing  glasses  for  the  past  eight  years,  off  and  on, 
which,  on  examination,  we  find  to  be  —  .75  cyl.  ax.  900. 

I  want  you  always  to  be  suspicious  of  weak  concave  lenses. 
I  want  you  almost  to  forget  that  there  are  such  lenses  in  your  trial 
case.  I  want  you  to  consider  the  refraction  of  every  case  that 
applies  to  you  as  hypermetropic,  until  positively  proven  otherwise 
I  want  you  to  be  afraid  of  concave  lenses  ;  they  should  be  marked 
with  the  skull  and  crossbones  poison  label  (just  as  morphia  is 
labeled  in  a  drug  store),  so  that  both  alike  may  be  used  with 
caution.  They  cannot  be  abolished  entirely,  but  the  (would  be) 
label  indicates  that  they  must  be  prescribed  with  the  greatest 
caution. 

When  I  meet  with  a  case  of  this  kind  wearing  concave  lenses, 
I  instinctively  jump  to  the  conclusion  that  some  one  has  made  an 
error,  and  I  pat  myself  on  the  back  as  being  smarter  than  the  other 
fellow.  Of  course,  I  am  wrong  in  my  hasty  jump  sometimes,  but 
then  no  harm  has  been  done,  and  I  am  clearing  the  tracks  so  that 
my  examination  may  be  commenced  and  continued  along  the 
proper  lines. 

A   JUSTIFIABLE    SUSPICION 

This  is  my  feeling  as  regards  the  case  before  us.  I  am  looking 
on  these  concave  cylinders  as  being  wrong,  and  I  am  thinking  to 
myself  that  they  should  never  have  been  given  to  this  gentleman, 
but  that  he  ought  to  be  wearing  convexes  instead.  Now,  we  will 
proceed  with  our  examination  and  see  if  our  conclusions  are  wrong, 
or  if  it's  the  other  fellow  that  has  made  the  error. 

We  find  the  acuteness  of  vision  to  be  :  O.  D.  £$  clearly  : 
O.  S.  £#  partly.  We  hand  him  the  reading  card,  and  note  his 
range  of  accommodation  for  the  smallest  type  to  be  from  4 '  _• " 
to  20". 

As  I  have  frequently  remarked  to  you  before  in  a  case  where 


Astigmatism  Against  the  Rtde  135 

astigmatism,  and  in  order  to  determine  its  presence  or  absence,  and 
in  accordance  with  our  routine  method  of  examination,  we  turn 
without  any  further  delay  to  the  ophthalmometer. 

We  locate  the  principal  meridians  at  900  and  1800,  and  find 
in  the  right  eye  that  the  curvature  of  the  horizontal  meridian 
exceeds  that  of  the  vertical  by  .50  D. ,  and  in  the  left  eye  by  .75  D. 

This  is  contrary  to  the  usual  order  of  things,  which  is  that  the 
excess  of  curvature  generally  lies  in  the  vertical  meridian,  and 
therefore  we  see  at  a  glance  that  this  is  a  case  of  astigmatism  and 
that  it  is  classified  as  "  against  the  rule." 

At  our  last  clinic  we  studied  a  case  of  astigmatism  with  the 
rule,  and  I  explained  to  you  at  some  length  just  what  was  meant  by 
the  term.  Now,  to-day  we  will  consider  this  case  of  astigmatism 
against  the  rule,  and  I  will  endeavor  to  be  just  as  explicit  in  my 
explanation  of  this  condition. 

When  there  is  a  difference  in  the  curvature  of  the  several 
meridians  of  the  cornea,  and  when  the  excess  of  curvature  lies  in  the 
horizontal  meridian,  or  in  a  ^meridian  either  way  within  4,5°  of  the 
horizontal,  the  case  is  one  of  -astigmatism ,  classified  as, against  the 
rule. 

DEFINITION    OF    ASTIGMATISM    AGAINST   THE    RULE 

In  other  words,  astigmatism  against  the  rule  simply  means 
that  thejvertical  meridian  of  the  cornea  is  less  curved  than  the 
horizontal,  in  contrast  to  the  condition  that  usually  obtains  where  it 
is  more  curved  ;  and  that  this  deficiency  of  refraction  in  the  vertical 
meridian  may  occur  in  any  form  of  astigmatism,  hypermetropic  or 
myopic,  simple,  compound  or  mixed. 

In  simple  hypermetropic  astigmatism  against  the  rule,  the 
ypermetropia  lies  in  the  vertical  meridian,  while  the  horizontal 
meridian  is  emmetropic.  The  vertical  meridian  is  less  sharply 
curved  than  the  horizontal,  and  hence  the  focus  of  the  vertical 
meridian  is  behind  the  retina,  while  the  focus  of  the  horizontal 
meridian  is  on  the  retina. 

While  the  refraction  of  the  horizontal  meridian  is  normal,  yet 
it  is  in  excess  of  that  of  the  vertical,  and  hence  corresponds  to  the 
definition  of  astigmatism  against  the  rule  which  we  have  given  you. 

In  compound  hypermetropic  astigmatism  against  the  rule,  the 
focus  of  both  meridians  is  behind  the  retina,  but  the  vertical 
meridian  being  the  more  hypermetropic,  focuses  farther  back. 
Now  in  this  case,  even  though  the  refraction  of  both  meridians  is 


136 


Clinics  i?i  Optometry 


below  normal,  yet  the  horizontal  being  the  least  hypermetropic,  its 
refraction  exceeds  that  of  the  vertical,  and  therefore  causes  the 
case  to  be  classified  as  against  the  rule. 

In  simple  myopic  astigmatism  against  the  rtcle,  the  vertical 
meridian  is  emmotropic,  and  focuses  on  the  retina,  while  the 
horizontal  meridian  is  myopic  and  focuses  in  front  of  the  retina. 
Therefore  the  refraction  of  the  horizontal  meridian  exceeds  that  of 
the  vertical,  and  thus  classifies  the  astigmatism  as  against  the  rule. 

In  compound  myopic  astigmatism  against  the  ride,  both 
meridians  are  myopic  and  both  focus  in  front  of  the  retina,  but  the 
horizontal  being  the  more  myopic,  focuses  farther  in  front.  In 
this  case  both  meridians  possess  an  excess  of  refractive  power  over 
the  normal,  but  the  horizontal,  having  the  greater  excess,  corre- 
sponds to  our  definition  of  astigmatism  against  the  rule. 

In  mixed  astigmatism  against  the  rule,  the  vertical  meridian 
is  hypermetropic  and  focuses  back  of  the  retina,  while  the 
horizontal  meridian  is  myopic  and  focuses  in  front  of  the  retina. 
The  excess  of  curvature  therefore  lies  in  the  horizontal  meridian, 
and  as  this  is  contrary  to  the  usual  order  of  things,  the  case  is 
classed  as  one  of  astigmatism  against  the  rule. 


THE    SHAPE    OF   THE   CORNEA 

In  all  of  these  five  forms  of  regular  astigmatism,  the  shape  of 
the  cornea  as  viewed  from  the  front,  is  that  of  an  oval,  with  the 
longest  meridian  in  the  vertical  direction. 


I  will  make  a  diagram  on  the  blackboard  to  represent  this 
condition,  and  will  ask  you  to  call  to  mind  each  form  of  astigmatism 
and  compare  it  with  the  diagram.  You  will  understand  that  the 
longer  the  curve,  the  flatter  it  will  be  and  the  less  its   refractive 


Astigmatism  Against  the  Rule  137 

power  ;  while  the  shorter  the  curve,  the  sharper  it  will  be  and  the 
greater  its  refraetive  power. 

In  simple  hypermetropic  astigmatism  the  vertical  meridian  is 
longer  and  flatter,  while  the  horizontal  meridian  is  emmetropic,  and 
exceeds  the  vertical  because  the  latter  is  below  par. 

In  compound  hypermetropic  astigmatism,  both  meridians  are 
hypermetropic,  the  horizontal  being  less  defective  than  the  vertical, 
and  hence  the  latter  has  the  shorter  and  sharper  curve. 

In  simple  myopic  astigmatism,  the  vertical  meridian  now  is 
normal,  and  the  horizontal  myopic  ;  therefore  the  latter  has  the 
shorter  and  sharper  curve. 

In  compound  myopic  astigmatism,  both  meridians  are  myopic, 
but  as  the  vertical  is  less  myopic  than  the  horizontal,  the  latter  has 
the  shorter  and  sharper  curve. 

In  mixed  astigmatism,  where  the  vertical  meridian  is  hyper- 
metropic and  the  horizontal  myopic,  the  latter  has  the  shorter  and 
sharper  curve. 

This  demonstrates  that  astigmatism  may  be  against  the  rule  in 
any  and  all  of  its  five  forms.  So  long  as  the  vertical  meridian  has 
the  longer  and  flatter  curve,  and  the  horizontal  the  shorter  and 
sharper  curve,  the  astigmatism  is  against  the  rule. 

I  have  gone  thus  minutely  into  the  point  of  astigmatism  against 
the  rule,  because  I  have  found  so  many  students  who  have  confused 
ideas  about  it.  A  great  many  of  our  text  books  make  but  slight 
mention  of  it,  and  attach  but  little  importance  to  it,  but  I  have 
found  it  of  great  value  in  instructing  students  and  making  the 
subject  clear  to  you. 

MENTAL    PICTURE    OF   THE    EYE 

The  optometrist  is  thus  enabled  to  picture  in  his  mind's  eye 
the  condition  of  the  curvatures  of  the  cornea  in  any  particular  case 
of  astigmatism,  and  the  location  of  the  focal  points  of  each  meridian 
in  relation  to  the  retina,  and  this  certainly  is  of  advantage  to  him 
in  the  adjustment  of  glasses  for  the  correction  of  the  particular 
defect  which  he  finds.  It  makes  him  think  of  the  eye  under 
observation,  rather  than  of  some  obstruse  rule  from  a  text  book. 

How  can  you  quickly  and  definitely  diagnose  a  case  of 
astigmatism  against  the  rule  ?  By  the  opthalmometer,  showing  that 
the  mires  overlap  in  the  horizontal  meridian,  or  at  least  are  closer 
together  than  in  the  vertical  meridian.     If   you  will  refer  to  the 


138  Clinics  in  Optometry 

diagram  on  the  blackboard  you  will  see  the  reason  for  this  approxi- 
mation of  the  images  in  the  horizontal  meridian  in  the  shortened 
radius  of  curvature  in  this  direction. 

Consequently,  when  you  are  looking  at  an  eye  through  the 
ophthalmometer,  if  on  turning  from  the  primary  to  the  secondary 
position,  you  see  the  mires  separate,  you  know  at  once  you  have  a 
case  of  astigmatism  against  the  rule,  because  this  separation 
indicates  a  longer  and  flatter  curve  vertically,  which  necessarily 
means  a  shorter  and  sharper  curve  horizontally  in  contrast. 

THE   TEST    CASE    EXAMINATION 

We  are  now  ready  to  proceed  with  our  test  case  examination. 
As  the  ophthalmometer  has  disclosed  the  presence  of  astigmatism, 
we  commence  at  once  with  cylinders,  and  as  the  instrument  has 
shown  the  defect  to  be  against  the  rule,  we  place  the  axis  of  the 
cylinder  in  the  horizonal  position. 

Our  patient  tells  us  that  +  .50  cyl.  axis  1800  produces  a 
noticeable  improvement  in  vision.  We  hold  a  +  -25  cylinder  over 
the  +  .50  cylinder,  expecting  it  to  be  accepted,  because,  as  I  have 
already  explained  to  you  at  a  previous  clinic,  in  astigmatism  against 
the  rule,  we  add  .50  D.  to  the  reading  of  the  ophthalmometer, 
which  in  this  case  in  this  eye  would  show  1  D.  of  astigmatism. 
But  to  my  surprise  this  additional  +  .  25  D.  is  rejected. 

In  such  a  case  you  must  try  a  concave  cylinder  with  axis 
placed  at  right  angles.  I  therefore  place  a  —  .25  D.  cylinder  with 
axis  at  900,  and  at  once  our  patient's  face  lights  up  and  he  says  the 
letters  are  very  much  plainer,  and  he  can  now  name  some  of  the 
letters  on  the  No.  20  line.  We  replace  this  —  .  25  cylinder  with  a 
—  .50  D.  cylinder  axis  in  same  position,  which  renders  the  No.  20 
line  perfectly  clear  and  legible. 

This  proves  the  case  to  be  one  of  mixed  astigmatism,  the 
vertical  meridian  being  .  50  D.  less  than  normal  and  the  horizontal 
meridian  .50  D.  above  normal,  the  difference  between  the  two 
meridians  being  1  D.,  as  indicated  by  the  ophthalmometer. 

The  vision  of  the  left  eye  is  not  as  good  as  the  right,  and  the 
ophthalmometer  discloses  a  greater  degree  of  astigmatism.  We 
place  +  .50  D.  cylinder  with  axis  at  180°,  which  is  at  once 
accepted;  we  hold  a  +  .25  D.  cylinder  in  front  of  it,  which  is 
still  better,  and  then  a  +  .50  D.  cylinder,  which  affords  still  greater 
improvement.     This  is  equivalent  to  a  -j-  1  D.  cylinder,  which  we 


Astigmatism  Against  the  Rule  1 39 

place  in  the  trial  frame  with  axis  at  1800,  with  which  vision  equals 
f$  almost. 

We  now  place  a  -f  .25  D.  cylinder  in  front  of  it,  and  this  is 
promptly  rejected.  But  as  the  ophthalmometer  indicates  a  greater 
degree  of  astigmatism  than  1  D. ,  we  try  a  —  .25  D.  cylinder  with 
axis  at  right  angles.  This  is  immediately  accepted  as  a  great 
improvement  and  makes  vision  f-°-,  every  letter  being  clear  and 
legible.  This  eye  also  presents  a  case  of  mixed  astigmatism,  the 
difference  between  the  two  meridians  being  1.25,  which  corresponds 
exactly  to  the  indications  of  the  ophthalmometer. 

TO    ASSURE    CORRECT    DIAGNOSIS 

In  the  early  part  of  our  lecture  I  called  your  attention  to  the 
concave  cylinders  the  patient  has  been  wearing,  and  told  you  they 
were  probably  wrong,  and  it  was  likely  they  should  be  convex 
instead.  Now,  since  we  have  completed  our  examination  you  will 
see  that  I  was  not  altogether  in  the  right  in  my  surmise,  nor  was 
the  other  fellow  altogether  in  the  wrong  in  his  prescription. 

It  is  perhaps  not  so  much  of  an  error  to  prescribe  concave 
cylinders  in  a  case  of  mixed  astigmatism  as  in  a  case  of  hyperme- 
tropic astigmatism.  Perhaps  you  might  be  inclined  to  regard  it  as 
only  half  an  error,  because  one  meridian  is  corrected  and  the  other 
not.  But  at  the  same  time  it  is  an  error,  and  especially  so  in  the 
left  eye,  where  the  hypermetropic  meridian  is  so  much  greater  than 
the  myopic.  If  only  one  meridian  was  to  be  corrected,  it  would 
have  been  much  better  to  correct  the  hypermetropic  meridian 
instead  of  the  myopic,  as  this  would  have  lessened  the  tax  on  the 
accommodation. 

Now  this  error  could  have  been  avoided  if  the  first  optometrist 
had  followed  out  the  method  of  examination  which  I  have  taught 
you  in  the  use  of  the  test  case,  and  that  is  always  to  commence 
with  convex  lenses,  either  spheres  or  cylinders.  In  this  case  the 
convex  cylinders  were  accepted  without  any  hesitation,  and  there 
was  no  need  to  turn  to  concave  cylinders  except  in  combination 
with  the  convexes. 

In  completing  our  examination,  we  use  the  ophthalmoscope, 
which  reveals  nothing  abnormal  in  the  fundus  except  a  slight  con- 
gestion, probably  due  to  strain. 

We  also  test  the  muscular  balance  by  means  of  the  Maddox 
rod,  and  find   i°  of  esophoria  and  i°  of  left  hypherphoria.      We 


140  Clinics  i?i  Optometry 

will  not  attempt  to  correct  these  muscular  anomalies  as  yet,  until 
we  see  what  relief  will  be  obtained  from  the  correction  of  the  mixed 
astigmatism.  Therefore,  we  will  order  (as  a  result  of  the  transpo- 
sition of  the  cross-cylinders) 

O.  D.  +  .  50  D.  sph.  O  —  1  D.  cyl.  axis  900 
O.  S.  -f  1  D.  sph.  O  —  1.25  D.  cyl.  axis  900 


Lenticular  Astigmatism 


[Clinic  No.  23] 

Mrs.  H.  H.,  aged  thirty  years,  in  good  health  apparently, 
complains  of  headaches  and  pains  in  the  eyes,  especially  after  using 
them  for  close  work. 

We  find  the  acuteness  of  vision  to  be  f$,  both  eyes  being  alike. 
Range  of  accommodation  for  Jaeger  No.  1  from  7  to  15  inches. 

In  accordance  with  our  custom,  we  ask  the  patient  to  be  seated 
at  the  ophthalmometer.  We  find  the  primary  position  and  meri- 
dian of  least  curvature  to  be  exactly  at  1800,  and  at  900  an  excess 
of  refracting  power  amounting  to  2.50  D.  This  classes  the  case 
as  one  of  astigmatism  with  the  rule. 

We  now  turn  to  the  trial  case  examination  and  commence  with 
+  .50  D.  cyl.  axis  at  900.  This  is  rejected  by  the  patient  as  being 
decidedly  worse.  In  this  case,  if  the  ophthalmometric  readings  are 
to  be  depended  upon,  a  minus  cylinder  with  an  axis  horizontal  is 
indicated.  We  try  a  —  .50  D.  cyl.  axis  1800,  which  is  accepted 
by  the  patient  as  being  noticeably  better. 

We  increase  —  .  25  D.  at  a  time,  each  change  affording  a  still 
greater  improvement  in  vision,  until  wereach  —  1.25D.  cyl.  axis  1800, 
with  which  vision  equals  f -§■  clearly.  We  must  not  order  a  stronger 
concave  lens  than  absolutely  necessary,  and  as  these  —  1.25  cylin- 
ders raise  vision  to  normal,  we  have  no  justification  in  trying  stronger 
ones. 

AN    INTERESTING    DISCREPANCY 

Now,  when  we  come  to  consider  this  case,  we  find  a  discrep- 
ancy between  the  amount  of  astigmatism  indicated  by  the  objective 
test  (ophthalmometer)  and  that  indicated  by  the  subjective  test 
(trial  lenses). 

You  will  perhaps  remember  at  one  of  our  previous  clinics, 
when  we  had  a  case  of  astigmatism  with  the  rule  before  us,  I  told 
you  we  must  deduct  .50  D.  from  the  reading  of  the  ophthalmometer, 
and  explained  to  you  the  reason  therefor.  By  making  such  deduc- 
tion in  this  case,  we  can  find  that  the  ophthalmometer  indicates 
2  D.  of  astigmatism,  while  the  test  lenses  disclose  only  1.25  D.  of 
astigmatism,  a  difference  of  .75  D. 


142  Clinics  in  Optometry 

This  case,  therefore,  must  be  considered  as  somewhat  exceptional. 
The  early  workers  with  the  ophthalmometer  believed,  in  the  majority 
of  cases,  that  the  total  astigmatism  and  the  corneal  astigmatism  were 
the  same.  But  a  further  and  more  extended  use  of  the  instrument 
soon  established  the  fact  that  there  is  a  difference  between  the  total 
astigmatism  and  the  corneal  astigmatism  of  about  .50  D.  or  .75  D. 

When  the  astigmatism js_ with  the_rjjle^JtheJ:otal  error  is  found  to 
be  .50  p.  less  than  the  corneal,  while  in  astigmatism  against  the  rule, 
the  total  defect  is  found  to  be .  50  D.  more  than  the  corneal.  The  axis 
of  the  total  astigmatism  usually  coincides  with  that  of  the  corneal. 

This  difference  between  the  total  and  corneal  astigmatism  led 
to  the  enunciation  of  the  rule,  with  which  you  are  all  now  familiar, 
to  add  or  subtract  .50  D. ,  as  the  case  was  against  or  with  the  rule, 
and  thus  make  the  objective  and  subjective  examinations  to  corres- 
pond. In  fact,  when  the  reading  of  the  ophthalmometer  is  verified 
by  the  test  case  examination,  you  may  feel  safe  in  prescribing  the 
glasses  thus  indicated. 

But  sometimes  there  is  a  discrepancy  between  the  results  of  the 
two  methods,  as  in  the  case  before  us,  and  then  it  becomes  a  matter 
of  interest  and  importance  to  investigate  the  possible  cause  of  such 
difference. 

LENTICULAR    ASTIGMATISM 

Among  the  several  causes  advanced  by  various  authorities,  the 
most  important  are  abnormal  lenticular  astigmatism,  and  astigma- 
tism of  the  posterior  surface  of  the  cornea.  It  is  to  the  first  of  these 
that  I  wish  to  direct  your  attention  to-day 

The  seat  of  astigmatism  may  be  either  extra-ocular  (when  on 
the  anterior  surface  of  the  cornea),  or  intra-ocular  (when  located  in 
any  of  the  refracting  media,  more  especially  in  the  crystalline  lens). 
Therefore,  the  total  astigmatism  is  made  up  of  the  sum  of  the  cor- 
neal and  lenticular. 

It  is  but  a  comparatively  short  time  since  Javal  and  other 
observers  established  the  fact  that  there  is  an  astigmatism  of  the 
crystalline  lens,  and  that  it  amounts,  as  a  rule,  to  .50  D.  or  .75  D. 
This  may  be  called  the  normal  astigmatism  of  the  lens,  just  as  we 
have  the  same  amount  of  astigmatism  normally  present  in  the  cor- 
nea. In  the  latter  case  the  excess  of  curvature  is  in  the  vertical 
meridian,  while  in  the  former  the  excess  is  in  the  horizontal  meri- 
dian, and  as  the  departure  from  normal  is  about  the  same  in  each 
case,  one  tends  to  neutralize  the  other. 


Lenticular  Astigmatism 


H3 


In  corneal  astigmatism  with  the  rule,  there  is  usually  associated 
a  lenticular  astigmatism  of  .50  D.  to  .75  D.  in  the  same  meridian, 
but  of  an  opposite  kind,  thereby  neutralizing  that  amount  of  corneal 
astigmatism. 

In  hypermetropic  astigmatism  with  the  rule,  it  is  the  horizon- 
tal meridian  of  the  cornea  that  is  flatter  or  hypermetropic,  while  it 
is  the  vertical  meridian  of  the  crystalline  lens  that  is  similarly 
affected.  In  other  words,  the  flatter  meridian  of  the  cornea  corres- 
ponds to  the  more  convex  meridian  of  the  lens,  and  the  more  con- 
vex meridian  of  the  cornea  to  the  flatter  meridian  of  the  lens. 


EXPLANATORY    DIAGRAMS 

In  the  non-astigmatic  eye,  the  vertical  meridian  of  the  cornea 
is  +  .50  D. ,  while  the  horizontal  meridian  of  the  cornea  is  emme- 
tropic. The  vertical  meridian  of  the  crystalline  lens  is  emmetropic, 
while  its  horizontal  meridian  is  -f  .50  D. 

I  will  make  a  diagram  on  the  blackboard,  which  may  perhaps 
serve  to  make  my  meaning  clearer  : 


VERTICAL 

HORIZONTAL 

Cornea  .    .    . 

+  .50  D. 

OO 

Crystalline    . 

00 

+  .50  D. 

+  .50  D. 

+  .50  D. 

The  refraction  of  the  two  meridians  is  thus  equalized,  the  astig- 
matism is  eliminated,  and  the  case  reduced  to  one  of  simple 
hypermetropia. 

Or  the  conditions  present  may  be  represented  by  the  following 
diagram  : 


VERTICAL 

HORIZONTAL 

Cornea    .    .    . 

+  .50  D. 

OO 

Crystalline  .    . 

-  .50  D. 

OO 

00 

OO 

144 


Clinics  in  Optometry 


Here  the  vertical  meridian  of  the  cornea  is  -f-  .50  D.  above 
normal,  while  the  vertical  meridian  of  the  crystalline  is  —  .50  D. 
below  normal,  resulting  in  an  elimination  of  the  astigmatism  and 
establishment  of  a  condition  of  emmetropia. 

Another  diagram  will  serve  to  illustrate  the  conditions  in  an 
astigmatic  eye,  with  the  rule. 


VERTICAL 

HORIZONTAL 

Cornea    .    .    . 

+  1.50  D. 

OO 

Crystalline  .    . 

—  .50.  D. 

OO 

+  1  D. 

OO 

In  this  case  the  refraction  of  the  vertical  meridian  is  reduced 
.50  D.,  but  the  astigmatism  still  remains,  being  lessened  only  in 
amount. 

In  astigmatism  against  the  rule,  the  conditions  present  may  be 
illustrated  by  the  following  diagram  : 


VERTICAL 

HORIZONTAL 

Cornea    .    .   . 

00 

+  -5o  D. 

Crystalline  .    . 

00 

+  .50  D. 

00 

+  i  D. 

In  this  case,  the  excess  of  curvature  in  the  cornea  lies  in  the 
horizontal  meridian,  as  it  does  also  in  the  crystalline  lens,  and 
therefore  as  the  astigmatism  is  in  the  same  meridian  and  of  the 
same  kind,  the  total  amount  of  defect  is  increased. 

CAUSES    OF    LENTICULAR    ASTIGMATISM 

The  question  may  occur  to  you  as  to  how  regular  lenticular 
astigmatism  is  caused.  It  may  be  produced  by  an  oblique  position 
of  the  lens,  by  a  slight  displacement  or  by  unequal  curvatures  of  its 


Lenticular  Astigmatism  145 

surfaces.  It  is  possible,  also,  to  have  a  dynamic  lenticular 
astigmatism  as  the  result  of  an  unequal  contraction  of  the  ciliary 
muscle. 

If  it  was  not  so  nearly  covered  by  the  iris,  the  position  of  the 
crystalline  lens  could  be  easily  determined.  A  case  has  been 
reported  of  complete  absence  of  the  iris  (aniridia),  in  which  the 
crystalline  lens  could  be  plainly  seen.  When  patient  first  came 
under  observation,  the  lens  was  vertical  and  not  displaced  at  all, 
but  in  the  course  of  a  year  or  two  it  became  luxated  upward  about 
1%  mm.,  and  the  upper  edge  tilted  slightly  backward.  On  this 
account  the  total  astigmatism  was  increased  1.50  D. ,  on  account  of 
the  increased  astigmatism  of  the  lens,  while  that  of  the  cornea 
remained  unchanged. 

It  is  a  fact  beyond  dispute,  that  in  nearly  all  cases  of  astigma- 
tism with  the  rule,  and  they  make  up  the  great  majority  of  all  cases 
of  astigmatism,  the  amount  of  corneal  astigmatism  shown  by  the 
objective  method  is  lessened  by  the  subjective  examination, 
undoubtedly  by  a  neutralizing  lenticular  astigmatism. 

Those  cases  of  dynamic  astigmatism  of  the  lens,  produced  by 
an  unequal  contraction  of  the  ciliary  muscle,  are  revealed  by  para- 
lyzing the  accommodation  by  atropine.  This  leaves  the  corneal 
astigmatism  unchanged,  and  at  the  same  time  it  lessens  or  removes 
the  lenticular  astigmatism. 

The  result  is  that  now  the  corneal  astigmatism  calls  for  a 
cylindrical  lens,  while  previously  such  lens  was  rejected  because  of 
the  neutralizing  effect  of  the  dynamic  lenticular  astigmatism,  which 
has  been  removed  by  the  action  of  the  mydratic. 

The  conditions  we  have  been  considering  are  where  the 
lenticular  astigmatism  is  present  to  the  normal  amount  of  .50  D.  or 
.75  D. .  diminishing  or  increasing  the  corneal  astigmatism  by  that 
amount,  as  it  is  with  or  against  the  rule.  I  have  already  explained 
to  you  how  the  readings  of  the  ophthalmometer  are  to  be  interpreted 
and  modified  in  accordance  with  these  well-established  facts. 

AN    EXCEPTIONAL    CASE 

But  in  the  case  before  us  I  have  made  these  deductions,  and  in 
spite  of  this  the  results  of  the  objective  and  subjective  tests  do  not 
agree.  The  ophthalmometer  showed  that  the  refraction  of  the 
horizontal  meridian  was  2.50  D.  less  than  the  vertical.  I  deduct 
the  customary  .50  D.   of   lenticular  astigmatism,  leaving  2  D.   of 


[46 


Clinics  in  Optometry 


astigmatism  with  the  rule,  but  the  subjective  examination  by  the 
test  case  showed  only  1.25  D.  of  astigmatism,  a  difference  of  .75  D. 

This  case,  therefore,  is  unusual  or  exceptional.  What  infer- 
ence can  we  draw  from  these  facts,  or  what  explanation  can  be 
offered  for  this  difference  ?  Most  likely  that  the  lenticular  astigma- 
tism, instead  of  being  .50  D.  or  75  D.,  as  usual,  amounts  to  1.25 
D. ,  the  excess  of  curvature  being  in  the  horizontal  meridian. 

I  will  make  a  diagram  on  the  blackboard  to  demonstrate  the 
conditions  present  in  this  case  : 


VERTICAL 

HORIZONTAL 

Cornea     .    .    . 

+  2.50  D. 

OO 

Cyrstalline  .    . 

-  1.25  D. 

OO 

+  1.25  D. 

OO 

If  you  will  consider  this  diagram,  you  will  see  that  the  astig- 
matism is  in  the  same  meridian,  but  of  opposite  kind.  The  cornea 
shows  an  excess  of  2.50  D.  in  the  vertical  meridian,  which  means  a 
myopia  of  this  amount  in  the  vertical  meridian.  The  crystalline 
shows  a  deficiency  of  1.25  D.  in  the  vertical  meridian,  which  means 
a  hypermetropia  of  this  amount  in  this  meridian.  The  hyper- 
metropia  neutralizes  a  portion  of  the  myopia,  and  leaves  1.25  D.  of 
defect  in  this  meridian,  to  be  corrected  by  a  concave  cylinder  with 
axis  at  right  angles. 

In  both  the  cornea  and  the  crystalline,  the  horizontal  meridian 
is  assumed  to  be  of  the  normal  curvature  or  emmetropic. 

This  is  one  case  where  the  lenticular  astigmatism  exceeds  the 
usual  amount  of  .50  D.  or  .75  D.,  and,  of  course,  there  are  others. 
The  lenticular  astigmatism  may  amount  to  2  D. ,  and  in  rare 
exceptions  to  even  more.  I  have  knowledge  of  one  case  being 
reported  where  it  reached  7.50  D.,  but  such  a  case  is  extraordinary. 

In  the  practice  of  optometry  you  must  be  prepared  for 
exceptional  cases.  Your  text-books  and  your  teachers  can  lay 
down  only  general  rules  for  your  guidance,  and  general  principles 
by  means  of  which  you  can  gain  an  orderly  knowledge  of  the 
science.     But  when  you  come  to  put  these  principles  into  practice, 


Lenticular  Astigmatism  147 

you  must  not  be  surprised  when  you  meet  with  cases  where  there 
are  variations  from  the  conditions  which  you  have  been  taught, 
sometimes  slight  and  sometimes  very  marked. 

AVOID    A    HASTY    CONCLUSION 

When  you  find  a  discrepancy,  you  must  not  too  hastily  con- 
clude that  it  is  due  to  lenticular  astigmatism.  For  instance,  you 
may  have  made  an  error  in  observation,  due  to  a  poor  light,  rest- 
lessness of  the  patient  or  an  improper  position  of  the  head  in  the 
headrest.  Or  an  accumulation  of  tears  will  cause  an  incorrect 
estimate  to  be  made.  If  the  tears  stand  in  the  groove  between  the 
lower  lid  and  the  ball,  the  ophthalmometer  may  read  astigmatism 
against  the  rule,  where  there  is  actually  astigmatism  with  the  rule. 
You  can  easily  understand  how  tears  may  alter  the  refractive  power 
of  the  eye,  because  they  form  the  first  refractive  surface  which  the 
light  strikes.  There  is  always  a  thin  layer  of  tears  covering  the 
cornea,  but  ordinarily  it  is  so  slight  and  in  such  close  contact,  that 
they  have  no  perceptible  influence.  But  when  they  collect  in 
excess  and  encroach  upon  the  lower  half  of  the  cornea,  they  may 
very  readily  alter  the  readings  of  the  ophthalmometer. 

Sometimes  the  instrument  may  be  at  fault,  as,  for  instance,  an 
imperfect  adjustment  of  the  bi-refractive  prism  in  the  telescope  :  on 
account  of  which,  no  matter  how  carefully  the  primary  position  is 
obtained,  the  secondary  position  would  show  false  results. 

Or  if  the  arc  was  not  adjusted  to  exactly  coincide  with  the  line 
of  doubling  of  the  prism,  it  would  be  impossible  to  make  the 
images  line  in  any  position  of  the  instrument.  Or  the  prisms  and 
lenses  of  the  ophthalmometer  may  be  made  of  imperfect  material. 

But  these  errors  can  be  overcome,  and  no  matter  how  perfect 
the  result  of  the  objective  examination,  it  must  be  verified  or 
disproved  by  a  subjective  examination,  which  if  properly  made,  is 
after  all  the  court  of  last  resort.  Both  methods  of  examination  are 
important  and  neither  can  be  dispensed  with,  but  their  results  must 
always  be  interpreted  with  common  sense,  and  free  from  adherence 
to  any  fixed  rules  or  notions. 


A  Case  of  High  Myopia 


[Clinic  No.  24] 

E.  C.  is  a  school  girl,  aged  eleven  years.  She  holds  every- 
thing very  close  to  her  eyes  and  is  unable  to  see  the  black- 
board in  school.  Her  father  tells  us  she  has  been  wearing 
glasses  for  the  past  six  years.  We  neutralize  them  and  find 
them  to  be  —  5  D.  spheres.  This  girl,  as  you  see,  is  a  delicate- 
looking  child,  but  makes  no  complaint  other  than  her  inability  to 
see  clearly. 

As  might  be  expected,  she  is  unable,  without  glasses,  to  see 
any  of  the  letters  on  the  test  card  hanging  across  the  room.  We 
ask  her  to  approach  the  card  slowly,  and  when  about  eight  feet 
from  it  she  is  able  to  name  the  large  letter  at  the  top.  We  therefore 
record  her  visual  acuity  as  ^f^- 

We  ask  her  to  return  to  her  chair,  and  testing  each  eye 
separately  with  concave  lenses,  we  find  for  right  eye  —  12  D. 
affords  a  vision  of  yW,  and  for  the  left  eye  —  18  D.  the  same 
acuteness  of  vision. 

This,  then,  is  a  case  of  high  myopia,  a  very  serious  condition 
of  refraction  for  the  patient,  and  possessing  many  points  of  interest 
to  the  optometrist. 

This  is  the  one  error  of  refraction  in  which  an  ophthalmoscopic 
examination  is  of  the  highest  importance,  in  order  to  determine  the 
condition  of  the  interior  of  the  eye,  and  the  presence  of  the  myopic 
crescent,  choroidal  atrophy,  macular  disease,  opacity  of  the  vitreous 
humor  or  other  accompaniments  of  staphyloma. 

Myopia,  as  you  all  know,  is  ordinarily  due  to  excessive  length 
of  the  antero-posterior  diameter  of  the  eye,  and  we  are  able  to 
estimate  pretty  accurately  the  amount  of  lengthening  by  the 
number  of  the  lens  required  to  correct  the  myopia,  according  to  the 
following  standard,  that  every  3  D.  lens  represents  very  closely 
one  millimeter  of  lengthening  of  the  antero-posterior  diameter  of 
the  eye. 

In  this  little  girl's  case,  the  lenses  just  accepted  would  indicate 
4  mm.  of  lengthening  in  the  right  eye,  and  6  mm.  of  lengthening 
in  the  left  eye. 


A  Case  of  High  Myopia  149 

Inasmuch  as  hypermetropia  is  regarded  as  an  imperfectly 
developed  condition,  so  it  might  seem  fair  to  look  upon  the  myopic 
eye  as  one  that  has  undergone  excessive  development  ;  but  the 
fact  of  the  matter  is  that  in  the  vast  majority  of  cases,  the  excessive 
length  is  due,  not  so  much  to  overgrowth  as  to  stretching  and 
distention  of  the  ocular  coats. 

Much  discussion  has  occurred  as  to  how  this  stretching  has 
been  caused,  and  the  various  theories  that  have  been  advanced  are 
divisible  into  two  general  classes  : 

1.  Those  which  attribute  the  deleterious  effect  to  the 
prolonged  exercise  of  the  accommodation. 

2.  Those  which  attribute  this  effect  to  the  convergence. 

The  supporters  of  the  first  theory  argue  that  the  intra-ocular 
pressure  is  increased  during  accommodation,  and  that  distention  of 
the  sclerotic  is  due  to  the  long  continuance  of  this  abnormal 
pressure  ;  that  the  act  of  accommodation  causes  traction  to  be 
exerted  upon  the  choroid,  thereby  giving  rise  to  chronic  inflamma- 
tory changes  with  subsequent  atrophy  and  thinning  of  the  choroid 
and  sclerotic  ;  that  spasm  of  accommodation  is  an  important  factor 
in  the  causation  of  myopia. 

All  of  these  have  been  denied,  and  a  potent  argument  against 
the  accommodation  theory  lies  in  the  fact  that  there  is  no  increase 
of  refraction  in  those  eyes  where  the  accommodative  effort  is  the 
greatest,  namely  in  hypermetropia. 

INFLUENCE    OF    CONVERGENCE 

I  am  inclined  to  regard  the  influence  of  the  convergence  upon 
the  shape  of  the  eyeball  as  of  more  importance  than  the  accommo- 
dation. When  the  internal  recti  are  strongly  contracted  in  the 
function  of  convergence,  the  external  recti  closely  bind  the  outer 
halves  of  the  balls,  and  at  the  same  time  the  two  obliques  must 
increase  their  effort  in  order  to  prevent  the  balls  from  sinking  back 
into  the  orbits.  The  pressure  upon  the  eyes  is  thus  increased  and 
traction  made  upon  the  posterior  part  of  the  sclerotic  by  the 
oblique  muscles. 

These  efforts  of  accommodation  and  convergence  are  common 
to  all  who  use  their  eyes  for  close  work,  but  as  a  matter  of  fact 
only  a  certain  proportion  of  them  become  myopic,  and  therefore  it 
is  necessary  to  assume  the  assistance  of  a  predisposing  cause  in 
those  eyes  which  do  become  elongated. 


150  Clinics  in  Optometry 

A  large  broad  skull  and  a  great  interpupillary  distance,  render 
convergence  more  difficult  and  thus  present  a  predisposing  element. 

Heredity  is  another  predisposing  factor  to  myopia  ;  this  does 
not  mean  that  the  babe  is  born  myopic.  On  the  contrary,  the  eye 
is  very  likely  to  be  hypermetropic  at  birth,  but  what  the  child 
inherits  is  a  tendency  to  myopia  on  account  of  weakness  of  the 
coats_of  the  eye  or  a  subnormal.,  resisting  power  of  the  sclerotic. 
Such  eyes  give  way  under  a  strain  that  would  be  harmless  to  a 
strong-coated  eye. 

So  great  is  the  elongation  in  the  higher  grades  of  myopia  that 
the  sclerotic  is  reduced  to  extreme  thinness,  and  on  account  of  the 
underlying  choroid  it  assumes  a  bluish  tint.  This  protrusion  back- 
ward of  the  myopic  eye  is  termed  posterior  staphyloma. 

The  conns  \s  a  whitish  crescent  (known  as  the  myopic  crescent) 
found  at  the  border  of  the  optic  nerve  ;  or  instead  of  being  crescent 
shaped,  it  may  entirely  surround  the  optic  disk.  This  is  due  to 
stretching  and  atrophy  of  the  choroid,  allowing  the  white  sclerotic 
to  show  through.  The  presence  of  a  conus  may  be  regarded  as 
evidence  of  congenital  deficiency  in  the  resisting  power  of  the 
sclerotic. 

TESTING    THE    CASE 

We  will  now  return  to  our  case  and  make  a  more  careful  and 
thorough  test  with  the  trial  lenses  ;  but  before  doing  so  we  will  call 
the  ophthalmometer  to  our  aid  to  determine  the  presence  or  absence 
of  astigmatism.  This  instrument  shows  an  excess  of  curvature  in 
the  vertical  meridian  of  2.50  D.  in  the  right  eye,  and  1.50  D.  in 
the  left.  This  indicates  astigmatism  with  the  rule,  and  if  a  concave 
cylinder  is  called  for  the  axis  would  be  placed  at  1800. 

We  place  a  —  10  D.  in  front  of  the  right  eye,  and  hold  before 
it  alternately  a  —  1  D.  sphere  and  a  —  1  D.  cylinder  with  axis  at 
1800.  The  sphere  is  preferred  as  affording  the  better  vision.  We 
now  place  a  —  1 1  D.  in  the  trial  frame  and  repeat  the  process. 
We  keep  on  along  these  lines  until  finally  we  get  —  13  D.  Q  —  2 
cyl.  axis  1800  as  the  best  combination  we  can  find,  with  which 
our  little  patient  is  able  to  name  some  of  the  letters  on  the 
No.  60  line. 

We  repeat  the  test  in  the  same  way  with  the  left  eye,  taking 
plenty  of  time  and  exercising  great  patience,  with  the  following 
result  :  16  D.  sph.  C  —  '  C>'1.  ax's  1800,  with  which  vision 
equals  f£. 


A  Case  of  High  Myopia  151 

This  is  certainly  a  high  degree  of  myopia,  and  we  must  be  on 
our  guard  not  to  tax  the  eye  by  giving  the  glasses  too  strong. 
Therefore  we  will  slightly  reduce  the  sphere  and  order  as  follows  : 


O.  D. 

—  12  D.  S.  C  —  2D.  cyl.  axis  1800 

0.  S. 

—  14  D.  S.  O  —  1  D.  cyl.  axis  1800 

These  glasses  can  be  worn  only  for  distance,  while  for  reading 
we  will  have  to  modify  the  glasses  according  to  the  following  rule  : 
Substract  from  the  glasses  representing  the  full  measure  of  the 
defect  those  glasses  the  focus  of  which  represents  the  distance  at 
which  the  patient  desires  to  read  or  work. 

Now  the  usual  reading  or  working  distance  is  13  inches,  and 
the  glass  representing  this  distance  is  3  D.  and  therefore  this  is  the 
amount  that  is  subtracted  from  the  distance  lenses,  which  would 
make  the  prescription  for  reading  glasses  as  follows  : 


0.  D.  - 

-  9  D.  S.  C  — 

2  D.  cyl.  axis  1800. 

O.  S.  - 

-  11  D.  S.  O- 

-  1  D.  cyl.  axis  1800. 

SUGGESTIONS    FOR    PARENTS 

A  child  at  this  age  cannot  be  expected  to  change  her  glasses 
from  time  to  time  as  she  may  be  looking  near  or  far,  and  therefore 
we  will  suggest  to  her  parents  that  these  reading  glasses  be  worn 
constantly  while  at  school  and  at  play,  and  that  the  distance  glasses 
be  reserved  for  the  church  or  theater,  or  when  she  makes  some 
special  visit  where  her  best  vision  may  be  desirable. 

We  will  make  our  usual  test  of  the  muscle  balance  by  means 
of  the  Maddox  rod,  and  find  150  esophoria  and  1}^°  left  hyper- 
phoria. This  is  somewhat  unexpected,  as  ordinarily  esophoria  is 
associated  with  hypermetropia,  while  a  myopic  condition  of  refrac- 
tion gives  rise  to  a  divergence  of  the  visual  axes,  which  may  show 
itself  simply  as  an  exophoria  or  as  an  actual  divergent  squint. 

This  departure  from  parallelism  of  the  visual  axes  is  due  to  the 
disturbance  of  the  relations  that  should  normally  exist  between 
accommodation  and  convergence.  In  myopia  there  is  little  or  no 
need  of  the  accommodation  in  near  vision,  but  the  convergence 
must  be  used  the  same  as  in  an  emmetropic  eye.  The  convergence 
is  then  used  in  excess  of  the  accommodation,  which  leads  to  fatigue 
of  the  internal  recti  and  finally  insufficiency. 

Or  looking  at  the  matter  in  another  light  :  accommodation  and 
convergence  are  used  in  equal  proportion  in  the  normal  eye,  and 


152  Clinics  in  Optometry 

each  function  receives  the  same  nervous  impulse,  causing  an  equal 
effort.  Now,  in  myopia  the  divergent  rays  from  near  objects  are 
focused  on  the  retina  with  little  or  no  accommodative  effort.  For 
this  reason  there  is  no  call  for  innervation  of  the  ciliary  muscle,  and 
consequently  the  innervation  of  the  internal  recti  is  lessened  or 
checked  to  an  equal  degree.  Thus  relaxation  of  these  muscles  is 
produced,  and  the  eye  under  the  control  of  the  stronger  external 
recti  turns  outward. 

In  this  case,  however,  instead  there  is  a  decided  convergence 
of  the  visual  axes,  showing  that  the  normal  relation  that  should 
exist  between  the  accommodation  and  convergence  has  been 
destroyed  or  disturbed.  We  feel  as  if  some  attention  should  be 
given  to  this  imbalance  of  the  muscles,  but  on  account  of  the 
strong  concave  curves  that  are  called  for,  we  hesitate  to  order 
prisms  in  combination.  How,  then,  can  we  obtain  the  desired 
prismatic  action  ?     By  decentration. 

DECENTRATION 

As  soon  as  we  look  through  a  lens  at  any  place  except  its 
actual  optical  center,  the  prismatic  effect  of  the  lens  is  brought  into 
action.  If  the  lens  is  weak  and  the  curvatures  slight,  the  prismatic 
effect  is  inappreciable  ;  but  with  the  increase  in  power  and 
curvature  of  the  lens,  there  is  a  corresponding  increase  in  prismatic 
action.  In  the  case  before  us,  where  the  lenses  required  are  so 
strong,  we  can  get  very  considerable  prismatic  power  by  decen- 
tration. 

Now,  is  there  any  rule  to  guide  us  in  this  matter  ?  Of  course 
there  must  be,  in  order  that  we  may  know  exactly  what  we  are  doing. 

In  the  first  place,  a  concave  lens  may  be  considered  as  made 
up  of  indefinite  number  of  prisms  with  their  bases  out.  If  such  a 
lens  is  decentered  outward,  we  get  the  effect  of  a  prism  base  in  ;  if 
decentered  inward,  a  prism  base  out.  In  this  case  where  esophoria 
is  present,  we  want  a  prism  base  out,  and  therefore  we  must  order 
the  lenses  decentered  inward.  Now  the  question  occurs,  how  much 
shall  they  be  decentered  ? 

The  rule  is  that  for  every  decentration  of  one  centimeter  there 
will  be  as  many  degrees  of  prism  as  there  are  diopters  in  the  lens. 
This  means  that  a  1  D.  lens  decentered  1  cm.  would  produce  a 
prismatic  effect  of  i°,  and  a  3  D.  decentered  1  cm.  a  prismatic 
effect  of  30. 


A  Case  of  High  Myopia  153 

But  on  account  of  the  small  size  of  uncut  lenses,  a  decentration 
of  3  mm  is  all  that  is  possible,  and  therefore  we  had  better  word 
our  rule  in  accordance  therewith,  as  follows  :  a  1  D.  lens  decentered 
1  mm.  produces  a  prismatic  effect  of  .  1  D  (ySj),  and  a  3  D  lens 
decentered  1  mm.  a  prismatic  effect  of  .3D.  (T\).  Inasmuch  as 
the  size  of  the  lens  limits  the  decentration  to  3  mm.,  the  amount 
of  prismatic  power  it  is  possible  for  us  to  produce  is  .3°  (y3^)  for 
every  1  D.  of  refractive  power. 

In  this  case,  where  we  have  ordered  —  12  D.  for  the  right  eye 
and  —  14  D.  for  the  left,  we  can  produce  3. 6°  and  4. 2°  of  prismatic 
power,  respectively,  or  a  total  of  7. 8°,  almost  8°.  As  this  is  about 
one-half  the  amount  of  esophoria,  and  as  this  is  about  as  much  as 
we  usually  attempt  to  correct,  you  can  easily  see  that  a  decentration 
in  this  case  is  of  great  practical  value,  and  we  will  therefore  order 
the  lenses  decentered  inwards  3  mm. 

Now,  there  was  also  i}4°  of  left  hyperphoria,  which  we  can 
correct  in  the  same  way.  For  this  purpose  we  want  the  effect  of  a 
1  °  prism  base  down  over  the  left  eye.  We  get  the  effect  of  a  prism 
base  down  by  ordering  the  lens  decentered  upwards,  and  if  it  is 
decentered  1  mm.  we  get  a  prismatic  effect  of  1.4°,  which  is  just 
about  what  we  want. 

REMOVAL    OF    CRYSTALLINE    LENS 

In  considering  the  treatment  of  a  case  of  high  myopia  like  the 
one  before  us,  the  question  of  the  removal  of  the  crystalline  lens, 
which  has  recently  been  advocated,  presents  itself.  Theoretically, 
this  is  a  beautiful  plan  of  treatment,  as  in  this  way  the  excessive 
refraction  can  be  very  materially  reduced,  but  it  does  not  appeal 
very  strongly  to  the  average  patient,  and  therefore  it  is  scarcely 
likely  to  become  very  popular. 

Hundreds  of  cases  of  removal  of  the  crystalline  lens  have  been 
reported  in  Europe  and  especially  in  Germany.  So  far,  this 
country  has  furnished  very  few  cases  ;  one  reason  for  which  may  be 
found  in  the  fact  that  we  give  more  attention  to  the  careful  and 
painstaking  correction  of  errors  of  refraction  than  do  the  European 
optometrists. 

While  on  this  subject,  it  is  interesting  to  consider  the  amount 
of  myopia  that  would  be  suitable  for  operation,  The  least  degree 
of  myopia  in  which  extraction  of  the  lens  is  permissible  is  about 
12  D.     Of   course,  the  higher  the  degree,  the  greater  might  be 


154  Clinics  in  Optometry 

considered  the  need  for  operation.  But  at  the  same  time,  in  the 
higher  degrees  of  myopia,  the  accompanying  posterior  staphyloma 
impairs  the  integrity  of  the  coats  of  the  eye  so  greatly  that  the 
operation  is  attended  with  serious  risks,  such  as  hemorrhage  and 
detachment  of  the  retina. 

A  condition  approximating  emmetropia  may  result  from 
extraction  of  the  lens  in  myopia,  varying  from  12  D.  to  20  D. 
This  case  would  be  included  in  this  class,  if  the  conditions  demanded 
operation  ;  but  with  a  vision  as  good  as  this  child  enjoys,  we  would 
not  think  of  advising  operative  procedure. 

As  you  have  noticed  the  best  vision  we  have  been  able  to  obtain 
in  this  case  is  \%  partly,  and  this  leads  me  to  say  that  in  the  higher 
grades  of  myopia,  it  is  impossible  to  raise  vision  to  normal  by  any 
lens.  This,  perhaps,  may  be  comforting  knowledge  to  some  of  you 
who  have  vainly  tried  to  find  a  lens  or  a  combination  of  lenses  that 
would  afford  a  vision  of  f-g-  in  the  highly  myopic  cases  that  have 
come  under  your  care. 

There  are  two  reasons  for  this  : 

1.  The  impaired  integrity  of  the  retina. 

2.  The  diminishing  effect  of  strong  concave  lenses. 

Either  one  of  these  would  suffice  to  account  for  the  lessened 
vision,  while  the  two  together  only  serve  to  make  it  more 
pronounced. 

You  can  easily  understand  that  the  great  bulging  and  stretch- 
ing of  the  coats  of  the  eye,  causes  the~rods  and  cones  of  the 
retina  tcTbe  separated.  The  diminution  in  the  size  of  the  image  by 
a  strong  concave  lens  is  very  marked,  therefore  this  smaller  image 
impresses  fewer  of  the  rods  and  cones,  and  there  can  be  no  wonder 
that  the  vision  is  not  capable  of  being  raised  to  normal.  Indeed, 
the  wonder  rather  is  that  we  are  able  to  afford  as  good  a  vision  as 
we  do  with  the  strong  concave  lenses  we  are  compelled  to  prescribe. 


Keratoconus  or  Conical  Cornea 


[Clinic  No.  25] 

J.  E.  B.,  forty-six  years  of  age,  complains  of  headache 
and  indistinctness  of  vision.  He  says  he  has  been  wearing 
glasses  for  the  last  eleven  years,  and  that  previously  his  vision 
had  been  good.  A  glance  at  his  glasses  shows  them  to  be  strong 
cylinders. 

On  seating  him  at  the  usual  distance  from  the  test-card  and 
removing  his  glasses,  we  find  he  is  unable  to  name  the  large  letter 
at  the  top  of  the  card.  In  a  case  of  impaired  vision  like  this,  it  is 
desirable  to  determine  whether  the  refraction  of  the  eye  is  at  fault 
or  whether  the  defective  vision  is  dependent  upon  disease.  In  the 
pin-hole  disk,  we  fortunately  possess  a  method  by  which  this 
point  can  be  easily  and  quickly  determined. 

We  will  therefore  make  use  of  this  test  in  this  case.  You  will 
notice  that  I  do  not  place  the  pin-hole  disk  in  the  trial  frame, 
because  in  so  many  cases  I  have  found  that  the  patient  has 
difficulty  in  finding  the  opening  and  his  answer  is  that  he  can 
see  nothing. 

Instead,  I  prefer  to  give  the  disk  to  the  patient  to  hold  in  his 
hand,  while  he  covers  with  his  other  hand  the  other  eye.  In  this 
way  he  has  the  disk  entirely  under  his  control,  and  he  can  easily 
move  it  around  until  he  gets  it  directly  in  the  visual  line.  In  this 
way  there  is  admitted  into  the  eye  a  small  pencil  of  light,  which, 
passing  through  the  axis  of  the  refractive  system  of  the  eye,  forms 
a  clearly-defined  image  on  the  retina,  in  spite  of  any  errors  of 
refraction  that  may  be  present. 

Therefore,  if  the  pin-hole  improves  vision,  we  know  that  the 
refractive  system  of  the  eye  is  at  fault,  and  that  a  similar  or  greater 
improvement  in  vision  can  be  expected  from  glasses. 

If,  on  the  contrary,  there  is  no  improvement  in  vision  by  look- 
through  the  pin-hole  disk,  there  must  be  some  diseased  condition 
which  is  not  remediable  by  glasses,  so  that  no  matter  how  perfect 
the  image  that  is  formed  in  the  eye,  it  cannot  be  perceived  or  trans- 
mitted to  the  brain,  and  thus  the  case  is  classed  as  one  beyond  the 
province  of  the  optician. 


156  Clinics  in  Optometry 

USE    OF    THE    PIN-HOLE    DISK 

I  would  advise  you  in  cases  of  defective  vision  to  use  the  pin- 
hole disk  at  once,  and  discover  early  in  the  examination  whether  or 
not  the  case  is  one  of  refractive  error,  and  you  will  thus  save  much 
valuable  time  which  might  be  spent  in  trying  to  fit  a  case  that  could 
not  be  helped  by  glasses. 

Any  one  of  you  gentlemen  can  demonstrate  for  himself  the 
effect  of  the  pin-hole  disk.  Take  from  your  trial  case  a  strong 
convex  lens,  hold  it  close  to  your  eye  and  look  through  it  at  some 
distant  object,  as  the  test-card.  The  letters  will  all  be  indistinct,  in 
fact  will  be  entirely  blotted  out  ;  now  place  the  pin-hole  disk  in 
front  of  the  lens,  when  you  will  find  its  power  is  destroyed  and 
vision  is  restored  to  normal.  In  like  manner,  the  effect  of  a  strong 
concave  lens  will  be  neutralized,  as  will  also  the  effect  of  cylinders, 
whether  convex  or  concave. 

If  the  damaging  effect  on  vision  caused  by  imposition  of  strong 
lenses  can  be  thus  destroyed  by  the  use  of  the  pin-hole  disk,  you 
can  easily  understood  how  the  impaired  vision  of  refractive  errors 
can  be  improved  by  the  same  means. 

We  now  hand  the  pin-hole  disk  to  this  patient,  and  ask  him  to 
use  it  in  the  way  we  have  just  described.  The  result,  as  he  tells  us, 
is  O.  D.  T%°0-,  O.  S.  \%.  This  is  not  very  encouraging,  but  at  the 
same  time  it  demonstrates  the  possibility  of  some  improvement  in 
vision  by  means  of  carefully-adjusted  lenses. 

We  will  now  make  use  of  the  ophthalmometer.  I  find  great 
distortion  in  the  shape  of  the  mires,  and  I  am  unable  to  focus  them 
sharply.  This  shows  greatly  irregularity  in  the  curvatures  of  the 
cornea,  and  from  my  previous  experience  in  similar  cases,  I  recog- 
nize here  a  case  of  keratoconus  or  conical  cornea. 

I  am  unable  to  get  the  primary  position  of  the  mires,  or 
the  meridians  of  least  and  greatest  refraction  or  the  amount  of 
overlapping  in  the  latter ;  the  most  that  I  can  do  with  the 
ophthalmometer  is  to  locate  one  of  the  principal  meridians  in 
each  eye,  that  for  the  right  eye  being  at  750  and  for  the  left  eye 
at  1050. 

OPHTHALMOMETER    OF    GREAL    VALUE 

Before  the  days  of  the  ophthalmometer,  cases  like  this  with 
irregular  curvature  of  the  cornea,  presented  the  greatest  difficulties 
in  the  fitting  of  glasses,  but  the  perfected  instrument  of  the  present 
day  does  much  towards  overcoming  these  difficulties. 


Keratocomts  or  Conical  Cornea  157 

The  first  glance  through  the  ophthalmometer  reveals  the 
irregularity  of  surface,  and  at  the  same  time  we  gain  information 
about  any  regular  astigmatism  that  may  be  present.  In  this  case 
the  ophthalmometer  shows  the  presence  of  regular  astigmatism  in 
addition  to  the  irregular.  The  distortion  of  the  images  of  the  mires 
is  such  a  delicate  test,  that  the  slightest  irregularity  of  the  surfaces 
of  the  cornea  is  detected.  The  ophthalmometer  is  also  of  the 
greatest  value  in  finding  the  most  regular  part  of  the  cornea. 

In  many  of  the  cases  of  conical  cornea,  the  astigmatism  is  of 
such  a  high  degree  that  the  ophthalmometer,  as  now  constructed, 
is  only  capable  of  giving  the  relative  difference  of  the  dioptric  power 
of  the  two  chief  meridians  of  the  cornea,  and  not  absolute  and  exact 
measurements.  Nevertheless,  in  all  ordinary  cases  and  for  all  practi- 
cal purposes,  the  instrument  is  accurate  enough.  In  the  excep- 
tional cases,  the  difference  in  the  curvature  of  the  two  chief  meri- 
dians can  be  approximated,  as  can  also  the  position  of  the  two 
meridians. 

We  will  now  use  the  ophthalmoscope  in  this  case,  and  we  find 
the  shadow  crescent  of  conical  cornea  beautifully  shown  in  each  eye. 
In  the  right  eye  the  shadow  is  so  pronounced  as  to  suggest  an 
opacity  of  the  lens,  but  as  we  examine  by  oblique  illumination  the 
lens  and  cornea  show  perfectly  clear. 

The  details  of  the  fundus  are  but  indistinctly  seen,  with  either 
the  direct  or  indirect  method.  The  optic  disk  is  whitish,  and  is 
long  and  narrow  vertically,  but  I  can  see  only  parts  of  it  at  a  time, 
the  blood  vessels  and  background  changing  with  each  movement  of 
the  eye  or  the  ophthalmoscope.  There  are  no  opacities  in  the 
vitreous  humor. 

The  ophthalmoscope  is  of  no  value  in  the  estimation  of  the 
refraction,  while  the  retinoscope  is  utterly  useless,  as  we  cannot  get 
any  definite  reflections  or  movements.  The  subjective  test  with  the 
clock  dial  is  altogether  unsatisfactory.  The  value  of  the  ophthal- 
mometer is  greatly  limited,  but  it  has  pointed  out  to  us  the  location 
of  one  of  the  principal  meridians.  This  narrows  the  measurement 
of  the  error  of  refraction  down  to  the  subjective  tests  with  the 
test  case  and  trial  lenses. 

TESTING    WITH    TRIAL    LENSES 

We  will  commence  the  test  with  the  right  eye.  The  ophthal- 
mometer has  indicated  the  location  of  one  of  the  principal  meridians 


158  Clifiics  in  'Optometry 

at  75°,  but  has  given  us  no  evidence  as  to  whether  it  is  the  meri- 
dian of  least  or  greatest  refraction,  and  hence  we  will  have  to  start 
with  the  test  lenses  somewhat  empirically. 

We  place  a  +  1  D.  cylinder  in  the  trial  frame  with  axis  at 
750.  The  result  is  negative,  or  if  anything  a  still  greater  dimness 
of  vision.  We  then  rotate  the  cylinder,  and  the  patient  chooses 
1650  as  the  best  position  for  the  axis.  This  indicates  a  case  of 
astigmatism  against  the  rule,  the  vertical  meridian  (or  15°  from  it) 
being  flatter  or  hypermetropic.  We  add  a  .50  D.  cylinder  with 
axis  in  same  position,  and  still  another  .50  D.  cyl.,  both  of  which 
are  accepted,  and  with  this  -f-  2  D.  cylinder  we  have  reached  the 
limit  of  convex  acceptance,  but  so  far  have  produced  but  little 
improvement  in  vision. 

WHAT    THE    EXAMINATION    INDICATES 

Presuming  the  astigmatism  to  be  of  much  higher  degree,  we 
place  a  —  1  D.  cylinder  over  the  convex  cylinder,  with  axes  at 
right  angles.  This  makes  the  letters  considerably  brighter,  and  the 
acceptance  of  this  concave  cylinder  with  axis  at  900  (or  within  150) 
shows  the  horizontal  meridian  to  be  convex  or  myopic,  and  indi- 
cates astigmatism  against  the  rule  ;  or,  taken  in  connection  with  the 
convex  cylinder,  a  case  of  mixed  astigmatism  against  the  rule. 

We  increase  the  concave  cylinder  1  D.  at  a  time,  each  change 
producing  a  greater  improvement  in  vision  until  we  reach  —  6  D. 
cylinder,  which  is  the  strongest  cylinder  in  our  trial  case,  but  with- 
out affording  very  satisfactory  vision.  It  is  very  unusual  to  meet 
with  astigmatism  of  a  higher  degree,  and  therefore  stronger  cylin- 
ders are  but  seldom  called  for. 

Fortunately  we  have  a  three-cell  trial  frame,  which  holds  the 
two  cylinders  so  far  selected,  and  permits  of  an  additional  concave 
cylinder,  which  of  course  is  placed  with  its  axis  in  the  same  position. 
We  add  a  —  1  D.  cylinder,  which  affords  considerable  improve- 
ment ;  we  replace  this  with  a  —  2  D.  cylinder,  but  patient  is  in 
doubt  whether  this  is  any  better.  We  therefore  give  preference  to 
the  weaker  cylinder.      Our  combination  now  is  : 

R.  -f  2  D.  cyl.  ax.  1650  C—  7  D.  cyl.  ax.  750 

with  which  vision  equals  £&. 

With  the  concave  cylinder  divided  into  two,  it  is  almost  impos- 
sible to  rotate  together  in  order  to  determine  whether  or  not  they 


Keratoconus  or  Conical  Cornea  159 

are  placed  at  the  proper  meridian.  In  fact  we  are  unable  to  rotate 
the  convex  and  the  concave  cylinder  together,  and  under  such  cir- 
cumstances it  is  customary  to  transpose  to  the  equivalent  sphero- 
cylinder,  where  there  is  only  one  cylinder  to  rotate.  But  in  this 
case  the  transposition  yields  a  —  9  D.  cylinder,  and  unfortunately 
we  do  not  have  a  cylinder  of  this  strength  in  our  trial  case. 

THE    ONLY    ALTERNATIVE 

The  only  thing  we  can  do  is  to  take  our  strongest  cylinder 
( —  6  D. )  and  find  the  best  position  for  its  axis,  which  the  patient 
very  confidently  locates  at  750,  and  as  this  meridian  is  corroborated 
by  the  ophthalmometer,  we  have  no  hesitation  in  accepting  it  as 
correct. 

The  pin-hole  disk  showed  the  vision  of  the  left  eye  to  be 
capable  of  the  greater  improvement,  and  hence  we  commence  the 
test  of  this  eye  with  more  hope.  We  try  of  course  convex  cylin- 
ders first,  and  the  strongest  accepted  is  +  1.50  D.,  with  axis  at 
1 50.  We  then  use  the  concave  cylinders  with  axes  at  right  angles, 
increasing  1  D.  at  a  time  and  securing  greater  improvement  in 
vision,  until  we  reach  —  6  D.  cylinder,  axis  1050,  with  which 
combination  vision  equals  -|$.  We  cannot  transpose  to  a  sphero- 
cylinder,  and  then  verify  the  position  of  the  axis,  but  we  will 
have  to  use  the  —  6  D.  cylinder  alone,  with  which  the  axis 
is  quickly  located  at  1050,  which  is  verified  by  our  ophthal- 
mometry examination. 

AGE    A    CONSIDERATION 

This  man  is  forty-six  years  of  age,  and  some  correction 
must  be  given  for  the  presbyopia  that  is  usually  present  at  this 
age.  He  asks  us  if  he  cannot  have  his  glasses  in  the  bifocal 
form.  We  tell  him  these  would  not  be  satisfactory  in  view  of 
the  high  degree  of  defect  and  the  lowered  acuteness  of  vision. 
Instead  we  will  prescribe  -\-  1.50  D.  spheres  in  an  extra  front  for 
reading. 

This  seems  to  be  a  favorable  case  for  ordering  the  lenses 
ground  in  toric  form,  which  would  be  as  follows  :  the  front  surface 
of  the  lens  ground  with  a  +  5  D.  sphere  ;  the  posterior  surface  of 
the  lens  ground  toric,  —  12  D.  at  1050  and  —  3  D.  in  the  75th 
meridian. 


i6o 


Clinics  in  Optometry 


We  are  considering  the  right  eye,  and  in  order  that  you  may 
follow  me  and  understand  this  transposition,  I  will  make  two  dia- 
grams on  the  blackboard  : 


7£>. 


^*£) 


The  cross-cylinder  showed  +  2  D.  power  in  the  seventy-fifth 
meridian  and  —  7  D.  power  in  the  one  hundred  and  sixty-fifth 
meridian,  and  the  toric  lens  or  any  other  transposition  must  show 
the  same  power  in  the  same  meridians. 

Now  let  us  analyze  the  toric  combination 


Keratocoyms  or  Conical  Cornea  161 

The  -f-  5  D.  sphere  ground  on  the  anterior  surface  of  the  lens 
affords  +  5  D.  power  in  both  meridians.  The  —  3D.  ground  in 
the  seventy-fifth  meridian  reduces  this  meridian  to  +  2  D. ,  and  — 
12  D.  ground  in  the  one  hundred  and  sixty-fifth  meridian  changes 
this  meridian  to  —  7  D. ,  thus  showing  the  same  powers  in  each 
meridian  as  the  original  cross-cylinder.  This  toric  lens  will  be  of 
much  better  shape  than  the  cross-cylinder  or  its  equivalent  sphero- 
cylinder. 

As  conical  cornea  is  not  very  common,  I  am  glad  to  be  able  to 
present  this  case  for  your  study  and  observation.  Except  very 
rarely  it  is  not  a  congenital  disease,  but  makes  its  appearance  about 
the  tenth  year.  It  is  most  frequently  observed  between  the  ages  of 
fifteen  and  thirty.  This  gentleman  tells  us  his  vision  was  good  and 
he  did  not  commence  to  wear  glasses  until  about  fifteen  years  ago, 
which  would  make  his  age  thirty-one  when  it  was  first  noticed. 
The  statement  is  made  that  women  are  more  often  affected  than 
men. 

AS    TO    THE    CAUSE   OF    CONICAL    CORNEA 

The  cause  giving  rise  to  this  condition  is  not  known,  neither 
is  the  method  by  which  it  is  produced,  but  it  has  been  noted  that  a 
great  many  of  the  patients  who  have  been  affected  were  in  feeble 
health.  The  integrity  of  the  cornea  is  impaired  so  that  it  gives 
way  at  the  point  of  greatest  weakness,  which  is  usually  a  little  below 
its  center,  where  it  is  forced  forward  and  becomes  sharply  curved 
while  around  it  the  cornea  assumes  a  conical  form. 

If  the  protrusion  is  moderate,  the  cornea  maintains  its  trans- 
parency, or  shows  but  slight  opacity  on  oblique  illumination.  If 
the  protrusion  is  extreme  (and  it  is  said  to  amount  to  as  much  as  a 
half  inch  sometimes)  the  opacity  is  much  more  noticeable.  Both 
eyes  are  usually  affected  ;  the  protrusion  may  slowly  increase  for  a 
time,  then  become  stationary  and  perhaps  change  again  later  in  life. 

Its  most  important  effect  is  its  influence  on  the  acuteness  of 
vision  and  the  refraction  of  the  eye,  the  cornea,  on  account  of  its 
increased  curvature  and  displacement  forward,  renders  the  eye 
highly  myopic  and  astigmatic.  This  impairs  the  vision  so  greatly 
that  but  seldom  can  lenses  be  found  to  raise  vision  to  anything  like 
the  normal  standard.  The  lenses  giving  best  vision  are  usually 
strong  concave  spheres  combined  with  cylinders.  In  this  case,  as 
you  see,  the  strong  lens  is  a  concave  cylinder  combined  with  a  weak 
convex,  which  is  somewhat  exceptional. 


1 62  Clinics  in  Optometry 

While  on  this  subject  of  conical  cornea,  it  may  be  interesting 
for  you  to  know  that  many  years  ago  Sir  John  Henschel  proposed 
to  correct  the  refraction  by  placing  over  the  cornea  a  transparent 
shell  or  cup,  which  was  called  a  ' '  contact  glass. ' '  The  lens  was 
ground  in  the  shape  of  a  meniscus,  so  that  the  posterior  surface  fits 
the  front  of  the  eyeball,  somewhat  after  the  nature  of  an  artificial 
eye,  while  the  front  surface  is  ground  to  correct  the  refractive 
error.  Unfortunately  the  contact  glass  acts  as  a  foreign  body,  and 
on  account  of  the  irritation  which  it  produces,  cannot  be  long 
tolerated. 

As  optometrists,  you  are  not  so  much  concerned  in  the  surgi- 
cal aspect  of  conical  cornea,  but  it  will  be  interesting  for  you  to 
have  some  knowledge  of  the  operative  treatment. 

Sometimes  an  iridectomy  is  performed  for  the  purpose  of 
admitting  light  through  a  peripheral  portion  of  the  cornea,  thus 
limiting  the  diffusion  of  the  retinal  image. 

Attempts  have  also  been  made  to  flatten  the  cornea  by  excision 
of  a  small  piece  from  the  apex  of  the  cone,  or  by  touching  and  per- 
forating the  apex  with  the  galvano-cautery,  resulting  in  the  pro- 
duction of  a  flattened  cicatrix. 

The  extended  use  of  myotics  seems  to  act  favorably  in  cases  of 
conical  cornea,  the  progress  of  which  they  moderate  or  check  by 
reducing  the  tension  of  the  anterior  chamber.  And,  besides,  they 
tend  to  improve  the  vision  by  contraction  of  the  pupil. 


The  Value  of  Retinoscopy 


[Clinics  No.  26] 

I  have  to  present  before  you  to-day  a  little  child,  Dorothy  B.  K. , 
five  years  of  age.  Her  father  tells  us  that  about  six  weeks  ago  he 
noticed  a  turning  in  or  convergence  of  the  left  eye. 

You  will  remember  I  have  always  taught  you  that  the  first  step 
in  the  examination  of  every  case  is  to  ascertain  the  acuteness  of 
vision.  Now  here  we  have  a  child  but  five  years  of  age,  and  her 
father  tells  us  she  does  not  know  her  letters.  It  is  therefore  a 
manifest  impossibility  in  this  case  to  determine  acuity  of  vision,  as 
this  depends  entirely  on  the  answers  of  the  patient  as  to  the 
smallest  letters  he  can  see  and  name.  Hence  we  will  be  compelled 
to  approach  and  handle  this  case  in  a  different  way. 

What  is  the  first  thought  that  occurs  to  you  ?  It  should  be 
that  this  is  a  typical  case  of  convergent  strabismus  dependent  upon 
hypermetropia.  In  former  times  and  even  at  the  present  day, 
many  curious  suggestions  have  been  made  by  anxious  parents  as  to 
the  cause  of  squint.  When  Bonders  published  his  great  work,  his 
"Accommodation  Theory,"  as  the  cause  of  convergent  strabismus, 
was  immediately  and  widely  accepted. 

ACCOMMODATION    AND    CONVERGENCE 

I  will  refresh  your  minds  with  a  brief  mention  of  the  principles 
involved.  In  the  emmetropic  eye  the  functions  of  accommodation 
and  convergence  are  closely  related,  so  that  with  every  effort  of 
accommodation  there  is  a  corresponding  effort  of  convergence. 
This  natural  association  of  the  two  functions  is  disturbed  in  both 
hypermetropia  and  myopia. 

A  hypermetropic  eye  in  a  state  of  rest  is  out  of  focus  for  all 
objects,  both  near  and  far.  Therefore,  such  an  eye  in  order  to  see 
distinctly,  must  use  its  accommodation  for  distant  vision  to  a  degree 
corresponding  to  the  amount  of  its  hypermetropia.  In  near  vision 
it  must  accommodate  both  for  the  hypermetropia  and  the  nearness 
of  object. 

The  excessive  amount  of  accommodation  required  under  such 
conditions  causes  a  proportionately  abnormal  amount  of  convergence 


164  Clinics  in  Optometry 

to  be  called  into  play.  There  was  only  enough  accommodation 
used  to  focus  the  print,  but  there  was  more  than  enough  convergence 
for  binocular  vision,  and  consequently  one  eye  fixed  the  object  and 
the  other  was  compelled  to  deviate  inwards. 

It  is  a  well-established  axiom  that  the  first  step  in  rectify- 
ing any  abnormality  is  to  seek  out  and  remove  the  cause. 
Therefore,  if  hypermetropia  is  the  cause  of  convergent  strabis- 
mus, a  correction  of  the  hypermetropia  will  cure  the  strabismus 
if  taken  hi  hand  early  enough,  and  herein  lies  the  whole  secret 
of  the  successful  management  of  convergent  strabismus  by  convex 
lenses. 

In  the  large  majority  of  cases  the  deviation  appears  very  early 
— that  is,  in  the  fourth  or  fifth  year,  just  about  the  time  when  the 
child  begins  to  use  its  eyes  in  near  vision,  and  that  is  the  time  when 
the  glasses  must  be  worn.  If  a  case  of  convergent  strabismus 
applies  to  you  after  the  age  of  ten  do  not  hold  out  any  hopes  of 
curing  the  condition  by  convex  lenses.  It  may  be  necessary  to 
order  glasses  for  the  correction  of  the  existing  hypermetropia,  but 
the  favorable  period  for  restoring  the  eyes  to  parallelism  has 
probably  passed. 

If  we  are  correct  in  our  diagnosis  that  this  case  is  one  of  con- 
vergent strabismus  caused  by  hypermetropia,  the  deviation  will 
probably  quickly  yield  to  the  restraining  influence  of  the  convex 
lenses  because  the  child  is  coming  under  treatment  at  the  age  most 
favorable  for  satisfactory  results. 

OBJECTIVE    METHOD    OF    EXAMINATION 

Therefore,  we  must  at  once  proceed  to  determine  if  hyperme- 
tropia is  present,  and  if  so  to  what  extent.  As  the  patient  is  too 
young  to  answer  questions,  or  at  least  that  dependence  may  be 
placed  on  her  answers,  the  subjective  method  of  examination  is  of 
little  or  no  value.  Instead  we  must  depend  upon  information  we 
gain  ourselves  by  direct  observation  of  the  action  of  the  eye,  and 
this  constitutes  what  is  known  as  the  objective  method  of  examina- 
tion. The  condition  of  the  refraction  of  an  eye  can  thus  be 
determined  by  the  observation  of  the  optometrist,  and  it  follows  as 
a  matter  of  course  that  the  correctness  of  the  results  depends 
largely  upon  the  skill  of  the  operator. 

Within  the  past  ten  or  fifteen  years  great  progress  has  been 
made  in  the  science  of  adapting  lenses  for  the  correction  of  refrac- 


The  Vahic  of  Retinoscopy  165 

live  errors,  and  this  advance  is  much  more  noticeable  in  the 
objective  methods  than  in  the  subjective,  the  former  being  the  more 
scientific  of  the  two.  And  of  all  the  objective  methods,  there  is 
none  more  exact  than  retinoscopy,  especially  in  the  hands  of  an 
expert.  Its  value  cannot  be  over-estimated  in  the  young,  in  the 
feeble  minded,  the  illiterate,  and  in  cases  of  nystagmus,  amblyopia 
and  aphakia. 

You  must  learn  retinoscopy,  both  theoretically  and  practically. 
There  may  be  some  who  can  learn  the  theory  and  yet  not  be  able 
to  put  it  into  practical  use,  but  it  is  scarcely  possible  for  any  one 
to  become  a  good  practical  operator  without  a  knowledge  of 
the  theory.  Both  theory  and  practical  application  should  be 
learned  together,  but  a  thorough  knowledge  of  the  former  should 
always  precede  the  latter. 

THE    RETINOSCOPE 

I  hold  in  my  hand  a  retinoscope,  which,  as  you  see,  is  simply 
a  mirror  to  project  light  into  the  eye,  with  an  aperture  for  the  eye 
of  the  observer,  and  without  the  disk  of  lenses  you  are  accus- 
tomed to  see  in  connection  with  the  ophthalmoscope.  While  the 
mirror  may  be  concave  or  plane,  the  latter  is  preferable. 

Concerning  the  source  of  light,  there  is  some  difference  of  opinion 
as  to  the  kind  and  condition  of  light  and  its  position,  but  I  feel  like 
saying  that  too  much  importance  has  been  attached  to  this  matter. 

As  you  see  we  use  here  a  sixteen-candle  power  electric  lamp 
with  frosted  globe  and  perforated  asbestos  chimney  ;  this  is  very 
convenient  and  always  ready  for  use,  but  if  electricity  is  not 
available,  a  Welsbach  gas  burner  or  an  oil  lamp  of  the  student  type 
would  answer  the  purpose  equally  well. 

The  light  may  be  on  either  side  of  the  face  or  above  the  head, 
but  it  should  be  behind  the  plane  of  the  eyes,  and  so  placed  that  it 
may  be  easily  and  quickly  projected  into  the  eye  of  the  patient  by 
means  of  the  retinoscope.  I  want  to  say  right  here  that  we  are  not 
so  much  concerned  in  the  character  of  the  entering  rays  as  in  the 
emergent  rays,  which  vary  in  accordance  with  the  refraction  of  the 
eye. 

Light  emerging  from  an  emmetropic  eye  the  rays  will  be 
parallel. 

Light  emerging  from  a  hypermetropic  eye,  in  which  there  is  a 
deficiency  of  refractive  power,  the  rays  will  be  divergent. 


1 66  Clinics  in  Optometry 

Light  emerging  from  a  myopic  eye,  in  which  there  is  an  excess 
of  refractive  power,  the  rays  will  be  convergent  and  will  come  to  a 
focus  at  some  definite  distance  at  what  is  called  the  far  point,  which 
can  be  located  by  the  optometrist  in  the  practice  of   retinoscopy. 

If  the  eye  is  not  naturally  myopic,  it  is  made  so  artificially  by 
interposing  certain  lenses,  by  which  the  far  point  is  located  at  some 
definite  distance,  which  is  called  the  working  distance.  By  common 
consent  this  is  placed  at  one  meter. 

This  child  is  so  small  that  we  will  ask  her  to  stand  up  instead 
of  allowing  her  to  be  seated,  as  we  usually  do,  and  as  I  sit  down 
her  eyes  and  mine  are  nearly  on  the  same  level.  We  face  each 
other  squarely  and  I  ask  her  to  look  not  at  me  nor  at  the  light,  but 
past  my  head  at  the  opposite  side  of  the  room. 

It  is  not  necessary  that  the  room  be  made  dark  as  night,  but  I 
will  ask  that  the  shades  be  drawn  down,  in  order  to  darken  the 
room  somewhat,  and  that  there  may  be  no  other  source  of  light  in 
the  room  during  the  test  except  that  used  in  connection  with  the 
instrument.  This  favors  a  dilatation  of  the  pupil,  so  that  we 
may  obtain  a  good  reflex. 

USE    OF    THE    RETINOSCOPE 

I  take  the  retinoscope  in  my  right  hand  and  rest  it  against  the 
side  of  my  nose  and  my  forehead  and  directly  in  front  of  my  right 
eye. 

It  might  be  well  to  mention  to  you  that  if  you  have  any  error 
of  refraction  in  your  own  eye  of  such  a  degree  as  to  impair  your 
visual  acuity,  it  is  desirable  that  you  wear  your  own  correcting 
lenses  in  using  the  retinoscope,  because  you  want  the  best  possible 
vision  in  studying  the  action  of  the  reflex.  This  may  prove  some- 
what annoying  at  first,  owing  to  the  reflections  from  the  surfaces  of 
your  lenses,  but  a  little  experience  will  enable  you  to  overcome 
this.  You  will  understand  that  your  accommodation  is  not  taken 
into  consideration,  but  simply  that  your  visual  acuity  may  be  good 
enough  to  enable  you  to  recognize  what  you  see. 

I  now  project  the  light  on  the  face,  and  I  must  say  to  you  that 
to  properly  control  this  beam  of  light  requires  considerable 
practice.  When  you  see  some  one  else  doing  it,  it  seems  like  a 
simple  matter  to  hold  the  mirror  so  that  the  light  will  reach  the  eye 
of  the  patient  ;  but  I  wish  to  warn  you  that  on  your  first  trial  of 
retinoscopy  you  will  find  some  difficulty  in  locating  the  eye. 


The  Value  of  Retinoscopy  1 67 

As  I  project  the  light  upon  the  eye,  you  will  see  a  circular 
spot  of  light  upon  the  face  surrounding  the  eye,  which  is  sometimes 
called  the  ' '  light  area. ' '  As  the  retinoscope  is  tilted  this  light  area 
is  made  to  move,  and  it  always  moves  on  the  face  in  the  same 
direction  as  the  mirror  is  tilted  ;  a  very  slight  movement  sufficing  to 
cause  the  light  to  pass  across  the  face  of  the  patient. 

HANDLING    THE    MIRROR 

Some  authorities  advise  that  the  retinoscope  be  held  firmly 
against  the  forehead,  and  the  desired  tilting  of  the  mirror  be  pro- 
duced by  a  movement  of  the  head,  to  the  right  and  left,  or  up  and 
down.  This  method  does  not  appeal  to  me,  as  the  movements  of 
the  optometrist's  head  give  the  appearance  of  awkwardness.  But, 
instead,  the  mirror  should  be  rotated  or  tilted  by  a  movement  of  the 
wrist  alone,  the  instrument  being  held  in  a  vertical  position  to  get 
the  side-to-side  movements,  and  in  a  horizontal  position  to  obtain 
the  up-and-down  movements. 

When  the  light  is  reflected  into  the  eye  of  the  patient,  the 
pupil  loses  its  darkness  and  becomes  luminous,  and  the  bright 
reflection  we  see  is  known  as  the  retinal  reflex.  Those  of  you  who 
are  close  to  me  can  see  the  light  area  on  the  face,  and  can  see  it 
move  as  I  tilt  the  mirror  ;  but  you  cannot  see  the  retinal  reflex  in 
the  pupil.  Only  the  eye  behind  the  sight  hole  of  the  retinoscope 
perceives  this,  because  the  emergent  rays  from  the  eye  under 
observation  pass  back  to  the  source  of  light  (the  mirror)  and  enter 
the  eye  of  the  observer  through  the  sight  hole. 

Now,  while  the  movement  of  the  light  area  upon  the  face 
is  always  in  the  same  direction  as  the  movement  of  the  mirror,  the 
movement  of  the  reflex  may  vary,  being  with  or  against  the  move- 
ment of  the  mirror,  according  as  the  emergent  rays  are  divergent 
or  convergent,  and  it  is  this  movement  of  the  reflex  that  determines 
the  refraction  of  the  eye. 

With  a  plane  mirror  retinoscope  at  a  distance  of  one  meter,  we 
obtain  the  following  indications,  which  I  will  mark  on  the  blackboard 
for  your  guidance  : 
No  movement  of  reflex  —  myopia  of  1  D. 

fEmmetropria, 
Hypermetropria, 
Myopia  less  than  1  D. 

Movement  of  reflex  "against"  —  myopia  over  I  D. 


1 68  Clinics  in  Optometry 

The  several  steps  which  I  follow  in  this  little  girl's  case  are  as 
follows  : 

i.  Illuminate  the  pupil  by  directing  the  light  full  upon  the 
eye,  so  that  the  pupil  is  in  the  center  of  the  light  area. 

2.  Rotate  or  tilt  the  mirror,  a  slow  movement  being  preferable, 
in  order  to  give  the  mind  time  to  interpret  what  the  eye  sees. 

3.  Note  whether  the  reflex  is  stationary  or  movable,  and,  if 
the  latter,  whether  with  or  against. 

If  there  is  a  movement  of  the  reflex,  find  lens  that  neutralizes 
the  same. 

In  this  case,  as  I  slowly  rotate  the  retinoscope  to  my  left,  I  see 
the  light  area  on  her  face  and  the  reflex  in  her  pupils  both  move  to 
my  left  ;  in  other  words,  the  movement  of  the  reflex  is  ' '  with  ' '  the 
light  area.  By  a  reference  to  the  table  on  the  blackboard,  you  will 
see  that  the  condition  of  the  refraction  in  this  case  is  either  emme- 
tropic, hypermetropic  or  myopic  less  than  1  D.  Now  we  must  use 
convex  lenses  to  determine  which  of    these  conditions  is  present. 

I  use  +  1  D.  lenses  first,  placing  them  in  the  trial  frame  in 
front  of  her  eyes.  I  again  rotate  the  mirror  and  cause  the  light  to 
travel  across  the  pupils,  and  find  the  movement  is  still  "with." 
Now  what  have  we  learned  ? 

We  know  that  the  eyes  are  hypermetropic,  and  we  have  by 
this  +  1  D.  lens  eliminated  both  emmetropia  and  myopia.  This 
lens  ' '  allows  ' '  for  the  distance  at  which  the  test  is  made,  and  it  is 
the  custom  of  many  skiascopists  to  commence  the  test  at  once  with 
this  lens  before  the  patient's  eyes,  in  order  to  save  time,  in  which 
case  no  movement  indicates  emmetropia,  with  movement  hyperme- 
tropia,  against  movement  myopia. 

Knowing,  then,  that  we  have  here  a  case  of  hyperme- 
tropia,  we  must  increase  the  strength  of  the  convex  lenses  until 
we  neutralize  the  movement.  We  replace  the  +  I  D.  spheres 
with  +  2  D.  and  find  the  movement  is  still  with.  We  now  try 
+  3  D.  and  find  the  movement  is  still  in  the  same  direction,  but 
with  a  +  4  D.  the  movement  is  neutralized.  In  order  to  make 
sure,  we  try  -f  4.50  D.,  with  which  the  movement  is  against, 
showing  over-correction.  We  then  try  +  3.50  D. ,  with  which 
the  movement  is  with,  showing  under-correction.  . 

Although  -f  4  D.  lenses  neutralize  the  movements  of  the 
reflex,  don't  jump  too  hastily  to  the  conclusion  that  they  represent 
the  degree  of  defect,  because  we  must  first  make  allowance  for  the 


The  Value  of  Retinoscopy  169 

working  distance,  and  this  is  done  by  adding  —  1  D.  to  the  findings 
of  the  retinoscope.  This  addition  is  made  in  all  cases,  whether  the 
neutralizing  lenses  be  convex  or  concave. 

PRESCRIBING    GLASSES 

In  this  case  we  have  the  following  problem,  which  I  will  place 
upon  the  blackboard  : 

-f  4  D,  S.      Retinoscopic  finding. 
Add  —  1  D.  S.     Allowance  for  working  distance. 
-f-  3  D.  S.      Amount  of  hypermetropia. 

This  is  algebraic  addition,  but  some  students  prefer  to  fix  the 
rule  in  their  minds  as  follows  :  In  hypermetropia  subtract  1  D.  from 
the  retinoscopic  findings,  and  in  myopia  add  1  D. 

Having  thus  measured  the  amount  of  hypermetropia  in  this 
case,  it  remains  to  prescribe  such  lenses  as  will  afford  comfort  and 
satisfaction,  and  at  the  same  time  check  the  tendency  to  excessive 
convergence.  There  is  room  for  difference  of  opinion  on  this 
point  ;  I  do  not  think  it  wise  to  attempt  to  force  the  eye  to  accept 
the  full  correction  at  once,  and  especially  in  a  child  who  has  never 
worn  glasses.  We  are  usually  guided  somewhat  by  the  effect  of 
the  convex  lenses  on  distant  vision,  which  would  be  impaired  by 
the  full  correction,  and  this  would  be  a  manifest  disadvantage  in  school 
work.  As  this  patient  is  unable  to  give  us  any  information  on  this 
point,  we  will  venture  to  correct  two-thirds  of  the  defect,  and  will 
order  -f  2D.  for  constant  wear,  and  will  emphasize  our  instructions 
to  the  father  that  Dorothy  should  not  be  allowed  to  remove  her 
glasses  during  waking  hours.  This  is.  not  so  much  on  account  of 
the  hypermetropia,  but  because  it  is  complicated  with  strabismus. 


A  Case  of  Pigmentary  Retinitis,  Illustrating  the  Value  of 
Ophthalmoscopy 

[Clinic  No.  27] 

A.  E.  S.,  aged  fifty-two  years,  wood-worker  by  occupation, 
German  by  birth.  This  is  the  name,  age,  occupation  and  nation- 
ality entered  on  the  card  of  the  patient  who  stands  before  us.  He 
complains  that  his  vision  is  poor  and  especially  so  at  night. 

After  some  questioning  we  are  able  to  get  a  history  of  this  case 
somewhat  as  follows  :  Vision  has  been  fairly  good  during  the  day, 
but  very  poor  at  night  except  in  a  very  bright  light.  He  has, 
therefore,  been  accustomed  to  remaining  indoors  at  night,  and 
occasionally  when  he  did  go  out  in  the  evening  he  never  left  the 
house  except  in  company  with  some  one  on  whom  he  could  rely. 
In  the  short  days  of  winter  he  hurries  home  before  twilight,  and  he 
has  learned  to  dread  dark  and  rainy  days.  He  came  to  this  coun- 
try when  a  boy,  and  he  remembers  he  had  this  night  blindness  at 
that  time,  but  he  feels  that  his  condition  has  been  gradually  getting 
worse.  He  has  been  fitted  with  glasses  a  number  of  times  but  with 
little  satisfaction.  He  is  a  single  man,  as  he  was  advised  by  phy- 
sicians never  to  marry,  as  his  eye  disease  would  probably  be  trans- 
mitted to  his  offspring. 

We  find  his  acuteness  of  vision  to  be  ^U}  the  same  in  each 
eye.  We  make  use  of  the  ophthalmometer,  which  shows  astigma- 
tism against  the  rule,  the  excess  of  curvature  in  the  horizontal  meri- 
dian being  about  2  D.  This  gives  us  a  pointer  as  to  the  condition  of 
the  refraction,  and  we  will  proceed  with  the  trial  case  to  work  it  out. 

If  convex  cylinders  are  required,  the  position  of  the  axis  would 
be  at  1800,  but  a  -f-  1  D.  cyl.  placed  in  this  position  is  rejected.  A 
rotation  of  the  cylinder  to  some  other  meridian  makes  vision  still 
worse.  We  then  try  a  concave  cylinder  axis  at  900,  and  this  is  at 
once  accepted.  This  shows  we  are  on  the  right  track  and  we 
increase  the  cylinder  and  after  a  few  trials  we  find  the  best  vision  is 
obtained  with  a  —  2D.  cyl.  axis  900,  with  which  V.  —  |J).  The 
test  of  the  right  eye  yields  the  same  result. 

Our  failure  to  raise  vision  to  normal  by  any  combination  of 
lenses,  and  the  history  of  poor  vision  given  us  by  the  patient,  leads 

170 


A  Case  of  Pigmentary  Retinitis  i 7 1 

us  to  suspect  some  diseased  condition,  and  in  order  to  determine 
this  point  we  must  make  use  of  the  ophthalmoscope. 

INVENTION    OF    THE    OPHTHALMOSCOPE 

Prior  to  the  invention  of  the  ophthalmoscope,  the  interior  of 
the  eye  was  an  unsealed  book.  The  ordinary  black  appearance  of 
the  pupil  was  supposed  to  be  due  to  absorption  of  the  light  by  the 
pigment  cells  of  the  choroid.  Doubt  was  first  thrown  on  this  idea 
about  a  hundred  years  ago  ;  various  observers  worked  upon  this 
problem,  but  it  was  not  solved  until  1851,  when  Helmholtz  con- 
trived an  eye  mirror,  by  means  of  which  he  was  enabled  to  illumi- 
nate the  eye  and  obtain  a  view  of  the  fundus. 

The  announcement  was  made  that  all  eyes  are  luminous,  but 
that  the  eye  of  the  observer  must  be  placed  in  the  path  of  the 
returning  rays.  This  is  accomplished  by  means  of  a  mirror  with  a 
perforation  in  it.  When  light  is  reflected  from  the  mirror  into  the 
eye,  it  returns  again  to  the  mirror  and  part  of  it  passes  through  the 
perforation  into  the  eye  of  the  observer  placed  behind  it. 

The  examination  of  the  fundus  by  means  of  the  ophthalmo- 
scope affords  important  information  not  only  in  intra-ocular  diseases, 
but  also  in  diseases  of  other  organs,  as  the  brain  and  kidneys,  and 
often  enables  us  to  detect  the  presence  of  syphilis.  Ophthalmoscopy 
to  be  of  value  requires  some  skill,  not  only  to  obtain  a  good  view 
of  the  fundus,  but  also  to  correctly  interpret  what  is  seen,  and  it 
increases  in  difficulty  as  we  pass  to  the  observation  and  interpreta- 
tion of  all  the  finer  changes  produced  by  disease. 

The  purpose  of  the  ophthalmoscope  is  to  obtain  a  good  view  of 
the  interior  of  the  eye,  and  therefore  in  the  selection  of  the  ophthal- 
moscope, I  may  say  to  you  that  it  is  not  at  all  necessary  to  purchase 
the  most  expensive  and  most  complicated  instrument,  but  I  can 
assure  you  that  the  small  ophthalmoscope,  such  as  I  hold  in  my 
hand,  will  answer  every  purpose. 

EVOLUTION    OF    THE    OPHTHALMOSCOPE 

It  is  well  for  you  to  have  some  knowledge  of  the  history  of  our 
science,  and  therefore  it  will  be  interesting  for  you  to  know  that  the 
original  Helmholtz  instrument  consisted  of  three  thin  plates  of  glass, 
which  formed  the  hypothenuse  of  a  triangular  box,  which  was  closed 
on  all  the  other  sides  and  blackened  in  the  interior.  The  small  side 
of  the  triangle  contained  an  eye-piece  for  the  use  of  the  observer. 


i^2  Clinics  in  Optometry 

At  the  present  time  this  instrument  is  little  more  than  a  curi- 
osity, having  given  way  to  the  improved  ophthalmoscopes  of  the 
present  day,  and  yet  by  reason  of  its  weak  illuminating  power,  it  is 
still  of  value  in  the  detection  of  fine  opacities  in  the  vitreous. 

The  most  popular  ophthalmoscope  is  the  Loring.  The  mirror 
is  concave,  having  a  radius  of  curvature  of  sixteen  inches  and  a 
focal  distance  of  eight  inches.  It  is  oblong  in  shape,  and  can  be 
tilted  to  an  angle  of  twenty-five  degrees.  A  concave  mirror  is 
preferable  because  it  gives  a  stronger  illumination. 

Considerable  stress  has  been  laid  upon  a  "dark  room,"  by 
which  we  understand  a  small  room  whose  walls  and  ceiling  have 
been  covered  in  black.  While  this  may  be  desirable,  it  is  not  at  all 
essential  ;  by  simply  drawing  the  shades,  you  can  convert  your 
office  into  a  dark  room,  as  occasion  requires,  that  will  answer  every 
purpose.  As  you  gain  in  experience  extreme  darkness  becomes 
less  necessary,  and  an  expert  ophthalmoscopist  often  makes  his 
examination  without  taking  the  trouble  to  draw  down  his  shades. 

For  illumination,  if  electricity  is  available,  it  is  certainly  the 
most  convenient.  A  frosted  glass  should  be  used  to  avoid  the 
annoying  reflection  of  the  wires  in  the  ordinary  lamp.  Gas  is  per- 
haps the  most  common  and  convenient  illuminant,  and  may  be  used 
in  connection  with  a  Welsbach  burner,  which  gives  a  beautiful 
illumination,  and  is  preferred  by  some  observers  to  electricity. 

If  gas  or  electricity  is  not  available,  an  argand  oil  lamp  will  be 
found  to  answer  the  purpose.  If  the  luminous  ophthalmoscope  is 
made  use  of,  the  question  of  light  is  settled  at  once,  as  this  instru- 
ment carries  its  own  lamp. 

Let  me  refer  again  to  the  mirror,  which  as  I  told  you  is  concave 
and  has  a  focal  distance  of  eight  inches.  Parallel  rays  falling  upon 
such  a  mirror  would  be  reflected  to  a  point  at  a  distance  of  eight 
inches  ;  and  conversely,  if  the  light  is  placed  eight  inches  from  the 
mirror,  the  rays  of  light  would  be  reflected  parallel.  If  the  light  is 
nearer  than  eight  inches,  the  rays  are  reflected  divergently. 

In  most  cases  we  make  use  of  convergent  rays,  which  are 
obtained  when  the  light  is  placed  farther  than  eight  inches,  the 
degree  of  convergence  increasing  with  the  distance  of  the  light. 

THE   USE    OF    MYDRIATICS 

In  the  various  works  on  the  ophthalmoscope,  which  are 
written    by  medical   men    for  medical    men,  constant    reference   is 


A  Case  of  Pigmentary  Retinitis  1 73 

made  to  the  use  of  mydriatics.  But  this  need  not  deter  you  in  the 
great  majority  of  cases  ;  after  a  little  practice  you  will  be  able  to 
make  an  ophthalmoscopic  examination  with  only  the  dilatation  of 
pupil  produced  by  the  darkened  room. 

The  optic  disk  is  the  landmark  first  looked  for  at  the  fundus  of 
the  eye,  and  fortunately  it  is  not  so  acutely  sensitive,  which  allows 
the  light  to  be  turned  in  this  direction  without  inconvenience,  and 
hence  this  part  can  be  most  easily  examined  without  a  mydriatic. 
This  is  in  contrast  to  the  sensitiveness  of  the  region  of  the  yellow 
spot,  as  shown  by  the  extreme  contraction  of  the  pupil  when  light 
is  thrown  in  this  direction  ;  in  addition  to  which  there  are  also  cor- 
neal reflections  which  often  interfere  with  the  view. 

We  will  examine  this  man's  eyes  first  by  the  direct  method, 
and  if  you  will  watch  me  closely,  you  will  see  the  various  steps 
necessary.  We  begin  our  examination  with  the  ophthalmoscope 
held  at  a  distance  of  twelve  or  fifteen  inches  ;  we  reflect  the  light 
into  the  eye  and  observe  the  red  pupil  reflex.  The  brightness  of 
this  reflex  may  be  modified  by  the  size  of  the  pupil,  the  transpar- 
ency of  the  media,  the  refraction  of  the  eye,  and  the  amount  of  pig- 
ment present.  In  this  case  I  find  the  reflex  not  nearly  so  bright 
as  from  a  healthy  eye. 

I  now  approach  the  patient  while  still  holding  the  ophthalmo- 
scope in  front  of  my  eye,  and  keeping  the  pupil  brightly  illumi- 
nated. The  beginner  will  find  some  difficulty  in  maintaining  the 
red  reflex  as  he  changes  his  position.  But  this  can  be  learned  by  a 
little  practice,  and  approaching  slowly  I  get  my  instrument  as  close 
to  the  patient's  eye  as  spectacles  are  worn.  The  direct  method  is 
so  called  from  the  fact  that  we  look  directly  into  the  eye. 

As  we  look  into  an  eye  with  the  ophthalmoscope,  what  do  we 
see  ?  The  normal  eye  ground  is  reddish  on  account  of  the  vascu- 
larity of  the  choroid  showing  through  the  transparent  retina.  The 
eye  ground  of  a  blonde  would  be  pinkish,  while  that  of  a  brunette 
would  be  much  darker,  on  account  of  the  difference  in  the  amount 
of  pigment  in  each.  The  usual  color  of  the  eye  ground  is  some- 
times described  as  "orange-red." 

EXAMINATION    OF   THE    OPTIC    DISK 

We  now  look  for  the  optic  disk  (sometimes  called  simply  the 
disk),  which  is  the  intra-ocular  ending  of  the  optic  nerve.  The 
actual  size  of  the  disk  is  1.5  mm.,  which  as  most  of  you  know  is 


i;4  Clinics  in  Optometry 

about  yV  of  an  inch.  Its  position  in  the  fundus  is  about  io°  or 
12°  to  the  inner  side  of  the  posterior  pole  of  the  eye.  It  corres- 
ponds to  the  normal  blind  spot  in  the  field  of  vision. 

The  shape  of  the  disk  varies  ;  it  may  be  circular  or  oval,  or 
perhaps  irregular  in  outline.  In  most  cases  it  is  slightly  oval  verti- 
cally. When  it  appears  decidedly  oval,  we  suspect  astigmatism^ 
In  health  the  margin  of  the  disk  is  distinct  and  well  defined. 

Near  the  center  of  the  disk  there  may  frequently  be  seen  a 
slight  depression,  and  as  it  is  not  abnormal,  it  has  been  termed  the 
"physiologic  cup."  It  is  caused  by  a  separation  of  the  nerve 
fibers  after  passing  through  the  lamina  cribrosa. 

At  the  bottom  of  the  cup  there  is  frequently  seen  an  area  com- 
posed of  little  gray  spots  (representing  the  optic  nerve  fibers), 
with  white  interspaces  ^representing  the  lamina  cribrosa),  which  is 
the  sclerotic  through  which  the  nerve  fibers  enter. 

Encircling  the  disk  may  be  seen  the  scleral  ring,  which  is  light 
colored,  or  the  choroidal  ring,  which  is  pigmented.  Either  of 
these  may  appear  in  the  form  of  a  crescent  instead  of  a  ring,  and 
they  may  be  present  or  absent. 

The  optic  disk  is  whitish  in  color  and  at  its  center  the  blood 
vessels  enter  and  radiate  over  the  retina.  The  veins  are  recognized 
as  being  larger  and  darker.  The  retina  being  transparent  is  almost 
invisible,  but  it  is  located  by  the  retinal  vessels. 

The  macula  lutea,  or  yellow  spot,  is  about  3  mm.  tothe  tem- 
poral side  of  the  disk.  It  is  oval  horizontally,  and  is  darker  in 
color  than  the  rest  of  the  fundus.  At  its  center  is  the  fovea  cen- 
tralis, which  is  very  small  and  appears  as  a  bright  spot. 

WHAT    THE    OPHTHALMOSCOPE    REVEALS 

I  am  now  in  position  for  direct  ophthalmoscopic  examination, 
and  as  I  look  into  the  eye  I  see  patches  of  pigment  scattered  all 
over  the  retina,  which  at  once  leads  me  to  make  a  diagnosis  in  this 
case  of  retinitis  pigmentosa,  or  pigmentary  degeneration  of  the 
retina.  The  changes  in  this  instance  are  more  degenerative  than 
inflammatory,  and  usually,  as  in  this  case,  both  eyes  are  affected. 

I  find  the  optic  disk  in  this  case  yellow  in  color,  and  the 
retinal  vessels  few  in  number  and  small  in  size. 

The  pigmentation  occurs  in  patches  and  is  deposited  in  the 
retina  along  the  course  of  the  blood  vessels.  In  the  early  stages 
of  the  disease,  the  characteristic  pigment  spots  are  at  first  seen  only 


A  Case  of  Pigmentary  Retinitis  175 

at  the  periphery  and  are  few  in  number  ;  but  as  the  disease  pro- 
gresses the  spots  increase  in  number  and  become  connected  to- 
gether by  branching  threads.  This  irregular  network  of  pigment 
slowly  creeps  towards  the  disk  and  at  last  invades  the  yellow  spot. 
In  the  case  of  this  man,  in  whom  the  disease  was  probably  con- 
genital, the  whole  fundus  is  pretty  well  covered. 

This  disease  is  also  marked  by  diminution  in  the  number  and 
size  of  the  retinal  vessels,  sometimes  contracted  to  mere  threads. 

The  further  progress  of  the  degenerative  changes  is  shown  by 
the  grayer  and  more  leaden  hue  of  the  fundus,  by  the  closer  and 
more  marked  network  of  the  pigment,  by  the  increased  atrophy  of 
the  disk,  and  by  the  further  diminution  in  the  size  of  the  retinal 
vessels.      There  is  also  great  contraction  in  the  field  of  vision. 

Usually,  the  diagnosis  of  a  case  of  this  kind  is  not  difficult. 
In  the  early  stages  when  the  deposit  of  pigment  is  scanty  and  con- 
fined to  the  periphery,  the  disease  may  be  overlooked.  But  a  little 
later  on,  when  the  disease  has  extended  to  the  more  central  parts 
of  the  field,  it  cannot  be  mistaken. 

Sometimes  the  disease  may  remain  at  a  standstill  for  years, 
but  usually  the  prognosis  is  unfavorable,  because  the  changes  pro- 
gress until  at  sixty  years  or  more  all  serviceable  vision  is  lost. 

PIGMENTARY    RETINITIS 

Let  me  briefly  enumerate  the  chief  subjective  symptoms  of 
pigmentary  retinitis.  The  first  to  attract  the  attention  of  the 
patient,  and  the  chief  characteristic  symptom  of  the  disease,  is  night 
blindness.  He  finds  his  vision  is  decidedly  poorer  as  soon  as  twi- 
light begins  and  after  the  sun  has  gone  down.  He  may  see  well  in 
daytime,  but  after  dark  he  stumbles  and  bumps  into  objects. 

After  a  time  his  vision  becomes  impaired  at  all  times,  and 
patient  appears  to  be  near-sighted  from  the  fact  of  holding  objects 
close  in  order  to  see  them  better. 

The  field  of  vision  becomes  markedly  contracted,  so  much  so 
that  patient  is  unable  to  go  out  alone. 

In  advanced  cases,  nystagmus  may  set  in,  which  is  shown  by  a 
rapid  lateral  oscillation  of  the  eyeballs. 

I  am  glad  to  have  the  opportunity  to  present  before  you  to- 
day this  case  of  retinitis  pigmentosa,  which  is  almost  typical,  both 
in  the  subjective  symptoms  and  in  the  ophthalmoscopic  appear- 
ances.     I  hope  this  case  will  make  impression  on  your  minds,  so 


176  Clinics  in  Optometry 

that  you  will  not  fail  to  recognize  the  disease  in  after  years  if   it 
should  fall  under  your  notice. 

This  is  distinctly  a  diseased  condition,  and  therefore  even 
though  you  are  able  to  raise  the  acuteness  of  vision  by  glasses,  I 
would  advise  you  not  to  prescribe  them,  but  rather  to  explain 
the  condition  to  the  patient  or  his  family,  and  shift  the  responsibil- 
ity of  such  a  serious  condition  to  a  medical  man. 


Albuminuric  Retinitis,  or  the  Retinitis  of  Bright's  Disease 


[Clinic  No.  28] 

H.  W.  H.,  aged  forty  years,  complains  of  foggy  vision  and 
that  he  has  been  unable  to  get  glasses  that  were  satisfactory.  First 
noticed  the   impairment  of  vision  about  six  months  ago. 

We  take  the  acuteness  of  vision  and  find  it  to  be  :  O.  D.  -gfo, 
O.  S.  flfc 

We  turn  to  the  ophthalmometer,  the  readings  of  which  are  50 
D.  excess  in  the  horizontal  meridian,  showing  the  existence  of 
astigmatism  and  classing  it  against  the  rule. 

We  return  to  the  test  case  and  after  a  few  trials  with  convex 
spheres  and  cylinders,  we  decide  on  the  following  formula  as  the 
best  we  can  do  : 

+  .50  D.  sph.  C  +  1  D.  cyl.  axis  1800 

The  same  for  each  eye,  raising  th£  vision  of  right  eye  to  T\<V  and 
of  left  eye  f&. 

This  result  is  unsatisfactory  both  for  us  and  the  patient.  We 
will  try  the  pin-hole  disk  in  order  to  ascertain  the  possibility  of 
further  improvement  in  vision,  but  the  result  is  negative,  as  the 
patient  says  he  cannot  see  as  well  through  the  pin  hole  as  with  the 
glasses  above-mentioned. 

A    DISEASED    CONDITION    INDICATED 

This  last  test  shows  the  presence  of  some  diseased  condition 
that  is  destroying  the  vision  and  interfering  with  the  action  of 
glasses.  Our  only  solution  of  the  case  lies  in  the  use  of  the 
ophthalmoscope. 

We  try  the  direct  method,  and  as  we  approach  closer  looking 
through  the  illuminated  pupil,  we  see  at  once  that  some  abnormal 
condition  is  present. 

As  customary,  we  look  first  for  the  optic  disk,  which  appears 
clouded  and  congested  and  somewhat  swollen.  We  also  see 
numerous  white  spots  and  patches  of  various  shapes  and  sizes. 
The  larger  spots  surround  the  disk,  while  in  the  region  of  the 
yellow  spot  they  appear  as  fine  white  dots  and  lines,  arranged  in 

177 


178  Clinics  in  Optometry 

the  shape  of  a  star  around  the  macula,  or  like  the  spokes  of  a 
wheel  with  the  fovea  as  the  center. 

We  also  see  extravasations  of  blood  scattered  here  and  there 
over  the  retina,  as  the  result  of  recent  hemorrhages. 

We  have  a  diseased  condition  here  sure  enough,  and  we  have 
no  trouble  in  locating  it  in  the  retina.  The  only  question  is  as  to 
the  form  of  retinitis,  and  from  my  experience  in  similar  cases  I  have 
no  difficulty  in  diagnosing  the  case  as  one  of  albuminuric  retinitis. 

Most  cases  of  retinitis  are  simply  incidental  symptoms  of 
general  constitutional  disease,  and  albuminuric  retinitis  is  one  of 
them.  This  is  a  disease  that  cannot  be  modified  by  glasses,  or 
even  any  local  treatment  of  the  eye,  but  on  account  of  its  serious- 
ness the  interest  of  the  optometrist  lies  largely  in  its  early  diagnosis. 

SYMPTOMATIC    OF    BRIGHT' S    DISEASE 

It  may  be  stated  as  a  general  axiom,  that  retinitis  occurs  most 
often  in  connection  with  albuminuria,  and  hence  the  ophthalmoscope 
becomes  of  the  greatest  assistance  in  the  diagnosis  of  inflammation 
of  the  kidneys,  because  albuminuric  retinitis  is  one  of  the  earliest 
symptoms  of  Bright' s  disease. 

Failure  of  vision  of  recent  occurrence  and  without  apparent 
cause,  should  lead  you  at  once  to  make  an  ophthalmoscopic  exam- 
ination, when  the  presence  of  retinal  disease  would  be  quickly 
detected,  and  if  of  the  albuminuric  variety  you  should  advise 
patient  to  consult  their  family  physician  for  an  examination  of  urine, 
in  order  that  your  diagnosis  may  be  corroborated.  It  has  been 
estimated  that  one-fourth  to  one-third  of  all  cases  of  kidney  disease, 
show  this  form  of  retinitis.  It  may  also  occur  in  the  nephritis  that 
accompanies  pregnancy,  and  that  following  scarlet  fever. 

Chronic  kidney  disease  is  a  very  serious  malady  that  comes  on 
gradually  and  insidiously.  When  in  an  advanced  stage,  it  is 
beyond  the  reach  of  medical  skill  ;  although  much  may  even  then 
be  done  to  prolong  life  and  relieve  suffering.  But  in  its  early 
stages  it  can  frequently  be  arrested  and  sometimes  radically  cured. 
Therefore,  any  aid  to  an  early  diagnosis  becomes  of  the  greatest 
importance,  and  no  warning  eye  symptoms  should  be  misunderstood 
or  disregarded. 

For  these  reasons  the  fact  should  be  known  to  every  optome- 
trist that  there  are  certain  changes  in  the  retina  that  are 
pathognomonic  of  disease  of  the  kidneys,  and  I  would  be  failing  in 


Albuminuric  Retinitis 


179 


my  duty  if  I  did  not  emphasize  this  statement,  so  that  it  may  be 
indelibly  impressed  upon  the  mind  of  every  member  of  this  class. 
Usually  both  eyes  are  affected,  but  varying  in  degree.  The 
ophthalmoscopic  appearances  bear  no  definite  relation  to  the  degree 
of  impairment  of  vision,  for  preservation  of  useful  sight  is  not 
incompatible  with  pronounced  changes  in  the  retina. 

SIGNIFICANCE    OF    ALBUMINURIC    RETINITIS 

The  detection  of  retinitis  is  not  o$ly  of  diagnostic  value,  but 
also  of  prognostic  importance  in  affections  of  the  kidneys.  It  has 
been  stated  upon  good  authority  that  life  is  rarely  prolonged  more 
than  one,  or,  at  most,  more  than  two  years,  after  the  development 
of  retinitis. 

When  retinal  hemorrhages  are  present,  the  prognosis  is  much 
more  unfavorable.  Hemorrhage  into  the  vitreous  and  detachment 
of  the  retina  may  also  occur,  but  these  conditions  are  not  common. 

Albuminuric  retinitis  also  occurs  in  pregnancy,  having  been 
observed  as  early  as  the  third  month,  although  it  is  more  frequent 
about  the  seventh  or  eighth  month.  As  this  is  a  serious  condition 
for  a  pregnant  woman  and  as  vision  is  not  always  impaired  early  in 
the  disease,  systematic  ophthalmoscopic  examinations  should  be 
made  during  the  course  of  pregnancy  whenever  albuminuria  exists. 

Authorities  agree  that  the  visual  disturbances  which  make  their 
appearance  during  the  last  weeks  of  pregnancy,  although  accom- 
panied by  the  same  retinal  changes,  are  of  less  grave  import  in  so 
far  as  sight  is  concerned,  because  in  the  great  majority  of  such 
cases,  vision  becomes  normal  after  labor. 

Albuminuric  retinitis  is  rarely  monocular  ;  both  eyes  are 
usually  affected,  but  not  always  commencing  at  the  same  time  or  to 
the  same  degree. 

The  prognosis  as  regards  the  vision  of  patient  and  his  life  are 
both  bad.  Vision  fails  gradually  at  first,  and  in  many  cases  this  is 
the  first  symptom  of  which  patient  takes  notice  and  which  draws 
his  attention  to  his  eyes  and  through  them  to  the  condition  of  his 
kidneys. 

The  duration  of  life  after  the  retina  has  become  affected,  is  but 
little  more  than  a  year  in  the  majority  of  cases,  although,  of  course, 
to  this  statement  there  are  many  exceptions.  Cases  have  been  known 
to  live  three,  five  and  even  eight  years,  after  the  onset  of  the  retinitis, 
when  due  to  specific  cause,  by  active  and  persistent  treatment. 


i8o  Clinics  in  Optometry 

Bright' s  disease  may  cause  a  retinitis  which  does  not  present 
exactly  the  characteristic  features  of  the  disease  as  I  have  mentioned 
them  to  you. 

In  some  cases  hemorrhages  may  be  the  most  conspicuous 
feature  scattered  over  the  fundus,  and  appearing  as  early  manifesta- 
tions before  the  disk  has  become  involved.  When  the  hemorrhages 
are  absorbed  the  spot  becomes  white,  and  if  the  underlying 
choroid  has  been  involved,  these  areas  may  be  partially  pigmented. 

In  other  cases,  it  is  the* inflammation  of  the  optic  disk,  which 
is  swollen  and  congested,  presenting  the  so-called  "choked  disk," 
or  papillitis,  as  it  is  sometimes  called.  The  edges  of  the  disk  are 
hazy  and  woolly. 

In  other  cases  the  only  changes  noticed  are  a  few  fine  spots 
about  the  macular  region  and  one  or  more  small  hemorrhages. 
Hence  in  any  case  where  the  ophthalmoscope  shows  signs  of 
retinitis,  the  patient  should  be  advised  to  have  careful  and  repeated 
examinations  of  the  urine  made. 

A    CASE    FOR    A    PHYSICIAN 

Albuminuric  retinitis  is  most  likely  to  occur  among  persons  of 
middle  age,  who  may  apply  to  you  for  glasses  for  impaired  vision, 
and  it  behooves  you  as  educated  optometrists  to  be  able  to  recog- 
nize the  presence  of  this  insidious  and  dangerous  disease,  in  order 
that  you  may  be  able  to  give  the  proper  advice  and  thus  reflect 
credit  on  yourself  and  your  profession,  while  giving  the  patient  the 
advantages  of  early  treatment  ;  instead  of  attempting  to  fit  glasses 
for  a  diseased  condition,  thus  losing  time  for  the  patient,  and 
bringing  yourself  and  your  profession  into  merited  disrepute. 

The  onset  of  the  symptoms  is  often  sudden,  corresponding  to 
the  occurrence  of  a  hemorrhage  or  swelling  in  the  region  of  the 
macula.  It  is  most  likely  that  there  are  evident  and  characteristic 
changes  in  the  fundus,  consisting  of  alterations  in  the  size,  course 
and  texture  of  the  blood  vessels,  which  precede  the  usual  symptoms, 
but  in  these  early  stages  there  is  little  to  attract  the  patient's 
attention  to  his  eyes,  and  ordinarily  relief  is  not  sought  until 
grosser  alterations  have  taken  place  so  that  vision  has  become 
perceptibly  impaired. 

The  pathological  changes  in  the  eye  are  primarily  in  the  blood 
vessels  and  consist  in  a  degeneration  of  their  walls,  and  involving 
the  vessels  not  only  of  the  retina  but  also  those  of  the  choroid  and 


Albuminuric  Retinitis  i8r. 

other  parts  of  the  eyeball.  The  whitish  spots  seen  with  the 
ophthalmoscope  are  usually  granular  or  fatty  tissue  degenerative 
products.  The  supporting  fibres  of  the  retina  become  swollen, 
infiltrated  and  also  degenerated.  There  is  serous  effusion  of  the 
retinal  structures.  The  nerve  fibres  are  swollen  and  contain 
degenerative  products  such  as  granular  or  fatty  particles. 

It  seems  probable  that  the  cause  of  all  these  changes  is 
fundamentally  an  alteration  in  the  character  of  the  blood  supplied 
to  these  tissues,  but  the  precise  nature  of  the  toxic  substances 
producing  them  has  not  yet  been  determined. 

During  the  course  of  Bright' s  disease,  periods  occur  when  the 
amount  of  urea  in  the  urine  is  considerably  diminished.  At  such 
times  there  is  usually  an  aggravation  of  all  the  symptoms,  both 
ocular  and  general. 

Whether  the  retinal  disease  is  due  to  the  retention  of  urea  or 
of  other  excretory  products  in  the  blood  is  an  open  question,  but  it 
has  been  observed  that  an  increase  of  urea  products  in  the  urine  is 
usually  followed  by  an  improvement  in  the  retinal  condition.  This 
does  not  prove  conclusively  that  the  urea  is  the  real  toxic  factor  in 
the  production  of  the  vascular  changes  in  the  retina  during  nephritis, 
but  it  at  least  serves  as  an  index  of  the  degree  of  toxaemia. 

CHARACTERISTIC    FEATURES 

In  summing  up  let  me  emphasize  the  characteristic  features  of 
albuminuric  retinitis  as  revealed  by  the  ophthalmoscope. 

r.  White  spots  and  patches.  These  are  well  defined,  of 
various  shapes  and  sizes,  and  occur  in  the  region  of  the  macula  and 
optic  disk.  In  typical  cases  they  are  arranged  in  lines  radiating  from 
the  center  of  the  macula,  sometimes  in  all  directions,  sometimes 
only  in  a  certain  portion  of  the  field.  Other  and  larger  spots  may 
be  seen  in  the  area  surrounding  the  disk.  These  may  coalesce  and 
form  a  ring-shaped  zone  around  the  disk. 

The  star-shaped  appearance  of  the  lines  radiating  from  the 
macula,  was  at  one  time  supposed  to  be  absolutely  characteristic  of 
Bright' s  disease,  but  too  much  dependence  must  not  be  placed 
upon  it  in  the  diagnosis,  as  it  sometimes  fails  to  appear  in  actual 
albuminuric  retinitis,  while  at  other  times  it  is  found  in  other  forms 
of  retinitis. 

The  white  massings  around  the  optic  disk  have  been  referred 
to   by  some   authorities    as    ' '  snow    banks, ' '    and    are   somewhat 


182  Clinics  in  Optometry 

peculiar  to  albuminuric  retinitis,  as  in  other  forms  of  retinitis,  the 
exudate  is  not  so  rounded  but  elongated,  and  follows  the  course  of 
the  large  vessels. 

2.  Hemorrhages.  Here  and  there  are  retinal  hemorrhages, 
occurring  at  any  time  during  the  progress  of  the  disease.  They 
may  be  rounded  or  flame-shaped,  occurring  in  the  nerve  fibre  layer 
and  in  the  neighborhood  of  the  vessels.  They  may  appear  as 
mere  flecks  of  blood  or  large  extravasations,  according  to  the 
intensity  of  the  disease.  Often  old  hemorrhages  in  the  shape  of 
pigment  spots  or  white  patches,  may  be  seen  along  with  fresh 
extravasations.  Small  hemorrhages  in  the  deep  layers,  when 
occurring  early  in  the  disease,  are  considered  as  unfavorable 
symptoms.  The  blood  may  disappear  by  absorption,  without 
leaving  any  white  or  pigmentary  remains. 

3.  The  optic  disk  may  be  unchanged,  but  it  is  more  likely  to 
show  evidence  of  congestion  or  inflammation,  presenting  the 
appearance  of  a  neuritis,  varying  from  a  slight  redness  with  blurring 
of  its  outlines  to  extreme  swelling  as  in  the  choked  disk  of  brain 
tumor.  When  the  disk  is  much  affected,  the  retinal  lesions  are 
generally  more  extensive  than  are  found  in  connection  with  neuritis 
from  other  causes. 

4.  The  appearance  of  the  retinal  vessels.  The  veins  are 
distended  and  often  tortuous.  The  arteries  may  be  normal  or 
sometimes  narrowed,  not  infrequently  showing  whitish  streaks  along 
one  or  both  borders,  which  in  some  places  may  obscure  the  vessel 
itself,  and  convert  it  into  a  white  cord.  The  vessels  may  be 
partially  buried  in  the  swollen  retina,  and  are  seen  to  cross 
the  white  patches  which  lie  in  the  outer  layers  of  the  retina, 
and  are  concealed  by  those  patches  which  lie  in  the  nerve  fibre 
layer. 

The  ophthalmoscopic  appearances  may  change  slowly.  The 
whitish  spots  may  gradually  increase  in  number  and  may  coalesce 
into  large  patches.  New  hemorrhages  may  appear  and  old  ones 
vanish.  In  general,  except  in  the  few  cases  that  recover,  the 
ophthalmoscopic  picture  becomes  more  and  more  complicated. 

RECOMMEND    PATIENT    TO    PHYSICIAN 

After  having  made  your  diagnosis  in  a  case  of  this  kind,  you 
must  refer  your  patient  to  a  medical  man  and  wash  your  hands  of 
any  further  responsibility. 


Albuminuric  Retinitis  183 

In  regard  to  treatment,  I  may  say  for  your  general  information, 
that  the  eye  should  have  rest,  as  in  any  other  form  of  retinitis. 

Errors  of  refraction  or  failure  of  accommodation  should  be 
carefully  met  by  proper  lenses,  to  be  worn  whenever  the  eyes  are 
used,  which  must  be  little.      Smoke  glasses  are  often  ordered. 

Beyond  this,  the  treatment  is  that  of  the  general  condition  : 
regulated  diet,  woolen  clothing,  a  dry,  mild  climate,  avoidance  of 
worry,  and  medicines  directed  to  the  renal  condition. 

The  subject  of  treatment  offers  but  little  of  comfort  either  to 
patient  or  physician  in  chronic,  well-marked  cases.  Still  it  must  be 
noted  that  periods  of  improvement  are  often  observed  in  the  course 
of  the  disease,  and  that  the  retinitis  of  acute  Bright' s  disease  or  of 
pregnancy,  may  entirely  clear  up  with  the  improvement  or  cure  of 
the  nephritis. 


Accommodative  Esophoria 

[Clinic  No.  29] 

This  young  lady,  Miss  Nanna  McK. ,  is  twenty-seven  years  of 
age.  She  complains  of  pain  in  eyes  and  headache,  and  says  she 
can't  see  well. 

We  find  the  acuteness  of  vision  in  each  eye  to  be  \ \  partly. 
On  examination  of  near  vision,  we  find  the  near-point  to  be 
six  inches.  This  recession  of  near-point  at  once  indicates  the 
presence  of  hypermetropia.  You  will  probably  recall  from  your 
study  of  the  amplitude  of  accommodation  at  the  various  ages, 
that  the  near  point  at  this  age  should  not  be  farther  than  five 
inches. 

We  turn  to  the  ophthalmometer,  which  gives  no  evidence  of 
astigmatism  beyond  the  normal  amount  of  slight  excess  in  the  ver- 
tical meridian  of  the  cornea. 

As  the  vision  is  so  nearly  normal,  we  can  exclude  myopia,  and 
as  the  ophthalmometer  shows  the  meridians  of  the  cornea  to  bear 
the  normal  relation  to  each  other,  we  may  exclude  astigmatism. 
The  diminished  amplitude  of  accommodation  points  to  hyperme- 
tropia, for  the  detection  and  measurement  of  which  we  will  now 
direct  our  efforts.  In  cases  like  this  where  the  patient  is  able  to 
name  some  or  all  of  the  letters  on  the  No.  20  line,  we  cannot 
expect  to  afford  much  improvement  in  vision  by  convex  lenses, 
because  any  hypermetropia  that  may  be  present  would  exist  in  the 
form  of  latent  rather  than  manifest  hypermetropia. 

METHOD    OF    EXAMINATION 

Therefore,  we  will  proceed  with  the  fogging  system,  with  the 
details  of  which  you  are  by  this  time  more  or  less  familiar.  We 
try  the  right  eye  first,  placing  before  it  a  +  5  D.  lens.  This  fogs 
vision  to  the  extent  of  blotting  out  the  whole  card  except  that  the 
No.  200  letter  can  be  guessed  at.  A  —  .50  D.  placed  before  it 
improves  vision,  and  we  increase  the  concave  lens  until  —  2.50  D. 
is  reached  when  the  No.  20  has  now  become  legible.  The  differ- 
ence between  the  two  lenses,  or  more  strictly  speaking  the  algebraic 
addition  of  the  lenses,  shows  the  amount  of  hypermetropia  we  have 


Accommodative  Esophoria  185 

been  able  to  uncover,  viz.,  2.50  D.  We  repeat  the  test  with  the 
left  eye  and  obtain  the  same  result. 

We  now  make  use  of  the  Maddox  rod,  placing  it  over  the  left 
eye  in  a  horizontal  position,  and  directing  the  patient's  attention  to 
the  small  point  of  light  across  the  room. 

We  ask  the  patient  on  which  side  of  the  light  the  red 
streak  appears,  and  she  replies  that  she  doesn't  see  any  red 
streak.  This  is  not  at  all  unusual  because  the  image  of  the 
uncovered  eye  is  so  much  brighter  that  it  entirely  occupies  the 
attention  of  the  brain  to  the  exclusion  of  the  distorted  image  of  the 
other  eye. 

But  an  inexperienced  man  must  not  get  discouraged  and 
jump  to  the  conclusion  that  he  is  therefore  unable  to  test  the 
muscle  balance.  We  simply  rotate  the  Maddox  rod  and  the  atten- 
tion of  the  brain  is  at  once  called  to  the  moving  object  and  the  red 
streak  caused  by  the  rod  becomes  visible. 

Now,  in  answer  to  our  inquiry,  she  is  able  to  locate  the  red 
streak  and  she  tells  us  it  is  away  off  to  the  left,  perhaps  a  foot  or 
more  from  the  light.  Now,  then,  what  have  we  ?  We  have  pro- 
duced an  artificial  diplopia  by  means  of  the  Maddox  rod,  and  the 
image  of  the  left  eye  (the  red  streak)  is  seen  to  the  left,  and  the 
image  of  the  right  eye  (the  natural  light)  is  seen  to  the  right. 
This  form  of  diplopia,  which  we  have  produced,  is  classed  as 
homonymous >  and  is  jdue  to  an  excess  of  convergence,  and  there- 
fore, we  have  here  a  case  of  esophoria. 

How  do  we  measure  the  amount  of  the  esophoria  ?  By 
the  strength  of  prism  base  out  that  is  necessary  to  bring  the 
red  streak  back  to  the  light.  We  try  a  50  prism  ;  this  brings 
it  closer,  but  it  is  still  to  the  left.  An  8°  prism  brings  it  still 
closer,  and  a  io°  prism  base  out  causes  the  streak  to  pass 
vertically  through  the  flame,  and  is,  therefore,  the  measure  of 
the  esophoria. 

In  spite  of  the  large  amount  of  esophoria,  we  have  in  this  case 
single  binocular  vision,  because  of_the  desire  on  the  part  of  nature 
for  single  vijiom If  the  need  for  this  desire  is  removed  by  exclud- 
ing one  eye  from  vision,  as  I  do  in  this  case  while  the  patient  looks 
at  the  letters  with  the  other  eye,  I  can  see  the  covered  eye 
deviate  inward.  As  I  remove  the  cover,  the  eye  quickly 
resumes  its  proper  position.  Such  a  condition  has  been  termed 
latent  strabismus. 


1 86  Clinics  in  Optometry 

LATENT    STRABISMUS 

When  the  inward  tendency  is  very  strong,  an  excessive 
strain  is  imposed  upon  the  nerve  centers  to  supply  sufficient 
innervation  to  the  external  recti  muscles  to  counterbalance 
this  tendency  to  extreme  convergence.  Beyond  a  certain  point 
this  effort  cannot  be  maintained,  and  vision  is  then  performed 
by  one  eye,  while  the  other  eye  deviates  inward,  or,  in  other 
words,  assumes  its  position  of  equilibrium.  This  constitutes 
manifest  strabismus. 

Latent  strabismus  may  become  manifest  at  certain  times,  as 
when  the  eyes  are  tired  from  prolonged  use,  and  especially  in  near 
vision,  when  spasm  of  convergence  may  be  excited  under  condi- 
tions similar  to  those  that  produce  spasm  of  accommodation. 
Under  normal  conditions  there  is  call  for  accommodation  and  con- 
vergence in  equal  proportion.  At  ten  inches  there  is  used  4  D.  of 
accommodation  and  4  M.  A.  of  convergence.  The  association 
between  the  functions  of  accommodation  and  convergence  is  so 
intimate  that  exercise  of  one  is  voluntarily  accompanied  by  a  cor- 
responding action  of  the  other. 

In  spite  of  this,  the  connection  between  the  two  functions  is 
not  so  strong  but  that  each  may  suffer  variation  within  certain 
limits,  and  thus  render  distinct  binocular  vision  possible  in  ametro- 
pia, where  one  or  the  other  function  needs  to  be  used  in  excess  of 
the  other. 

In  hypermetropia  excessive  convergence  is  provoked,  because 
the  inordinately  great  accommodative  effort  required  to  overcome 
the  diminished  refraction  and  maintain  distinct  vision  gives  rise  to 
the  impulse  for  more  convergence  than  the  distance  of  the  object 
demands.  This  excess  of  convergence  may  be  latent  as  in 
esophoria,  or  it  may  be  manifest  as  in  convergent  strabismus,  but 
in  either  case  the  common  cause  is  hypermetropia. 

When  we  release  the  eyes  from  the  necessity  for  binocular 
fixation,  and  allow  them  to  assume  their  positions  of  equilibrium, 
the  inward  deviation  manifests  itself  by  the  appearance  of  the 
diplopia  that  has  been  produced.  This  is  accomplished  by  making 
one  retinal  image  so  dissimilar  from  the  other  that  there  is  no  desire 
to  fuse  them  into  one.  This  we  have  done  in  the  case  before  us, 
and  you  will  remember  the  red  streak  seen  by  the  left  eye  appears 
to  be  way  off  to  the  left.      Inasmuch  as  the  eye  turns  toward  the 


Accommodative  Esophoria  187 

right,  it  would  seem  on  first  thought  that  the  object  seen  by  this  eye 
should  appear  to  the  right,  instead  of  the  left,  as  it  actually  does. 

HOMONYMOUS    DIPLOPIA   OF    ESOPHORIA 

As  this  seeming  contradiction  is  very  confusing  to  optical 
students,  I  think  we  can  spend  a  few  minutes  profitably  in  discuss- 
ing it.  I  can  possibly  make  the  matter  clearer  to  you  by  a  diagram 
on  the  blackboard  : 


Diagram  illustrating  the  homonymous  diplopia  of  esophoria 

In  this  diagram  you  will  see  that  the  light  from  the  candle 
falls  upon  the  yellow  spot  of  the  left  eye,  forms  an  image  there  and 
is  referred  back  in  the  direction  from  which  it  came.  The  rays 
from  the  same  candle  entering  the  right  eye  do  not  fall  upon  the 
yellow  spot  but  strike  the  retina  at  the  inner  side  of  it.  Now, 
then,  according  to  the  law  of  projection,  as  you  learned  it  while 
studying  the  physiology  of  vision,  the  light  is  referred,  not  in  the 
direction  from  which  it  actually  comes,  but  in  the  direction  from 
which  it  appears  to  come,  and  thus  is  seen  to  the  right.  An  object 
situated  to  the  right  impresses  its  image  on  the  left  of  the  retina, 
and  is  referred  by  the  brain  from  left  to  right.  An  object  situated 
to  the  left  impresses  its  image  on  the  right  of  the  retina,  and  is 
referred  by  the  brain  from  right  to  left. 

In  like  manner  when  an  impression  is  made  upon  the  upper 
part  of  the  retina,  it  is  referred  by  the  brain  to  the  lower  part  of  the 
field  where  the  object  lies  from  which  the  impression  is  received. 
When  an  impression  is  made  on  the  lower  part  of  the  retina,  it 
is  referred  upward. 


1 88  Clinics  in  Optometry 

And  so  in  the  case  under  consideration  where  the  impression 
is  made  on  the  retina  to  the  inner  side  of  the  yellow  spot,  it  is 
referred  outward.  This  is  the  law  of  projection,  and  it  is  by  this 
law  that  our  vision  is  erect  in  spite  of  the  fact  that  the  retinal  image  is 
inverted.  I  trust  that  you  will  all  now  understand  how  and  why  the 
false  or  second  image  is  seen  in  the  opposite  direction  from  the  de- 
viation, and  that  therefore  the  diplopia  of  esophoria  is  homonymous. 

The  symptoms  of  esophoria  are  not  distinctive  ;  slight  degrees 
may  give  rise  to  no  discomfort  whatever.  The  least  amount  which 
is  likely  to  cause  asthenopia  cannot  be  definitely  stated,  since  this 
will  vary  with  the  nervous  susceptibility  of  the  individual  patient. 
In  general,  it  may  be  said  that  an  esophoria  of  2°  or  30  is  not 
much  beyond  the  limits  of  normal  muscular  equilibrium,  when 
tested  at  a  distance  of  twenty  feet. 

.Headache  isa  symptom  of  esophoria,  coming  on  periodically 
and  sometimes  accompanied  with  vertigo  and  nausea.  It  occurs  after 
the_use  of  the  eyes  for  distant  vision  more  often  than  near  vision, 
and  is  due  not  so  much  to  extra  effort  of  the  internal  recti  as  to  the 
strain  placed  upon  the  external  recti  to  prevent  undue  convergence, 
as  otherwise  diplopia  is  likely  to  result.  This  may  afford  relief  to 
the  headaches  but  the  patient  will  be  greatly  annoyed  by  the  double 
vision.  The  strabismus  has  now  become  manifest  and  the  asthen- 
opia is  replaced  by  a  new  train  of  symptoms  originating  from  the 
loss  of  binocular  vision. 

But  the  diplopia  does  not  continue  ;  monocular  vision  is  soon 
established,  as  a  result  of  the  cultivated  habit  of  disregarding  the 
false  image,  which  is  greatly  favored  by  the  insensitiveness  of  that 
part  of  the  retina  upon  which  the  false  image  is  impressed. 

TREATMENT    OK    ESOPHORIA 

The  first  step  in  the  management  of  a  case  of  esophoria  is  the 
correction  of  any  existing  error  of  refraction  ;  and  especially  in  a 
case  of  accommodative  esophoria  like  the  one  before  us,  is  it  neces- 
sary to  correct  the  hyyermetropia  as  fully  as  possible,  and  thus  by 
lessening  the  innervation  of  the  accommodation  do  we  also  check 
the  tendency  to  excessive  convergence. 

Theoretically  we  would  prescribe  the  lenses  that  represent  the 
total  amount  of  error  we  have  been  able  to  discover,  but  practically 
such  lenses  are  too  strong  for  comfort  to  start  with,  and,  therefore, 
in  this  case,  we  will  order  +  1.50  D.  spheres  for  constant  wear. 


Accommodative  Esophoria  189 

Such  lenses  should  be  worn  long  enough  for  the  eyes  to 
become  thoroughly  accustomed  to  them  in  order  to  note  what 
benefits  are  derived  and  what  amelioration  of  the  unpleasant 
symptoms,  and  as  a  rule,  no  attempt  should  be  made  to  influ- 
ence the  muscles  by  means  of  prisms  until  all  the  improvement 
that  could  possibly  follow  from  the  spherical  glasses  has  been 
exhausted. 

When  prisms  are  required  for  the  correction  of  the  esophoria, 
they  are  placed  bases  out.  In  such  cases  when  the  muscles  are  at 
rest,  the  visual  lines  assume  the  excessive  convergence  produced 
by  the  muscle  imbalance  and  a  homonymous  diplopia  is  the  result. 
Prisms  bases  out  enable  the  eyes  to  maintain  binocular  single  vision, 
thus  avoiding  the  nervous  strain  which  is  otherwise  unavoidable  to 
maintain  and  not  to  exceed  the  proper  amount  of  convergence. 

If  the  esophoria  does  not  exceed  20  or  30,  it  will  not  call  for 
correction  by  prisms.  If  of  high  degree,  a  tenotomy  may  become 
necessary,  because  on  account  of  the  distorting  property  of  prisms, 
it  is  not  pleasant  to  wear  very  strong  glasses  of  this  kind,  50  for 
each  eye  being  the  limit  usually  allowed. 

The  proportion  of  the  esophoria  that  should  be  corrected  by 
prisms  varies  in  different  cases,  but,  as  a  rule,  it  should  not  be 
more  than  one-half  to  two-thirds  of  that  manifested  by  the  test  at 
20  feet,  which  usually  suffices  to  relieve  the  asthenopia,  whereas  a 
total  correction  would  not  be  tolerated. 

Prisms  prescribed  for  the  relief  of  esophoric  asthenopia .must 
ordinarily  be  worn  constantly/,  occasionally  in  esophoria,  which  is 
not  attended  by  spasmodic  action  of  the  internal  recti,  the  tendency 
to  excessive  convergence  disappears  in  near  vision,  and,  under  such 
conditions,  it  suffices  to  wear  the  prisms  for  distant  use  only. 

In  the  slighter  cases  of  esophoria  much  relief  is  afforded  by 
the  use  of  prismatic  glasses  ;  but  in  many  cases  the  excess  of  con- 
vergence is  so  great  that  only  a  small  proportion  can  be  corrected 
within  the  limits  allowed  for  such  lenses.  In  some  cases  where 
relief  is  afforded  at  first,  a  greater  amount  of  esophoria  becomes 
manifest  under  the  relaxing  influence  of  the  prisms,  so  that  the 
strength  of  the  latter  must  be  increased  until  the  limit  is  reached, 
and  then  other  methods  of  treatment  must  be  sought. 

Cases  of  ^ophoriajusually  occur  in  connection  with  hyperme- 
tropia  or  some  other  form  of  ametropia,  in  which  cases  the  prisms 
are  combined  with  the  refracting  lenses,   or  rather  the   necessary 


190  Clinics  in  Optometry 

lens  curvature  is  ground  upon  the  surfaces  of  the  desired  prismatic 
correction. 

In  this  case  we  will  combine  prisms  with  the  desired  spheres, 
and  especially  as  we  do  not  feel  justified  in  prescribing  lenses  strong 
enough  for  a  full  correction. 

Our  prescription  will  read  as  follows  : 

^S  o  *  >  -\-  1.50  D.  S.  O  prism  2°  base  out. 

This  corrects  a  little  less  than  half  the  esophoria,  but  on 
account  of  the  unpleasantness  (to  the  patient)  of  prisms,  we  prefer 
not  to  order  them  too  strong  at  first. 


Spasm  of  Accommodation 


[Clinic  No  30] 

This  patient,  Miss  Mary  H. ,  is  twenty-five  years  of  age.  She 
tells  us  her  glasses  have  been  changed  three  times  during  the  past 
year.  The  new  glasses  would  seem  satisfactory  at  first,  but  soon 
she  was  able  to  see  better  at  a  distance  without  them.  Complains 
of  pain  in  her  eyes  and  headache  whenever  she  attempts  to  use  her 
eyes  either  with  or  without  glasses.  The  pain  in  her  head  nearly 
sets  her  wild  when  she  tries  to  concentrate  her  vision  on  a  distant  or 
a  near  object.  Has  been  able  to  do  but  little  reading,  writing  or 
sewing  for  the  past  year.  Has  been  under  treatment  by  specialists 
in  gynecology  and  neurology,  but  they  find  but  little  departure 
from  normal  conditions.  The  suggestion  has  been  made  that  she  is 
hysterical.  She  sleeps  well  and  has  a  good  appetite,  but  occa- 
sionally suffers  from  nausea  and  vomiting  if  she  uses  her  eyes  for 
any  great  length  of  time.  The  patient  is  apparently  in  good 
physical  condition,  on  account  of  which  she  receives  but  little 
sympathy  from  her  family  or  friends,  and  she  therefore  almost  seems 
provoked  with  her  apparent  good  health  as  not  being  consistent 
with  her  suffering. 

You  will  remember  the  first  step  in  the  actual  examination  of 
a  case  is  to  ascertain  the  acuteness  of  vision,  which  in  this  case  we 
find  to  be  |^,  being  the  same  for  each  eye. 

We  next  measure  the  amplitude  of  accommodation,  which  we 
find  to  be  10  D. ,  depending  upon  a  near  point  of  four  inches,  as 
measured  from  the  eye  to  the  reading  card,  which  is  approximated  as 
close  as  it  is  possible  to  decipher  the  small  type  at  the  top  of  the  card. 

We  turn  to  the  trial  case  test  and  find  convex  lenses  are 
rejected  as  blurring  the  distant  vision.  We  commence  with  +  -25 
D. ,  which  is  refused  ;  in  spite  of  this  we  try  stronger  lenses,  but 
each  increase  of  strength  blurs  vision  still  more.  We  try  each  eye 
separately  and  find  the  result  the  same. 

There  seems  to  be  nothing  else  but  to  try  concave  lenses, 
which  we  will  proceed  to  do,  but  only  for  the  purpose  of  pointing 
a  moral.  These  lenses  are  quickly  accepted,  and  we  soon  find  that 
—  1  D.  raises  the  vision  to  normal. 


1 92  Clinics  in  Optometry 

We  now  test  the  muscle  balance  by  means  of  the  Maddox  rod, 
according  to  our  usual  custom.  The  rod  being  placed  over  the  left 
eye,  the  patient  tells  us  the  streak  is  about  six  inches  to  the  left  ; 
after  a  few  trials  we  find  that  a  prism  of  40  base  out  is  required  to 
bring  the  streak  back  to  the  flame,  which  then  represents  the  amount 
of  esophoria.  We  repeat  the  test  with  the  —  1  D.  lenses  in  the 
trial  frame  :  now  the  patient  says  the  red  streak  is  farther  to  the  left 
and  a  50  prism  base  out  is  required  to  bring  it  back.  The  correc- 
tion of  the  apparent  defect  by  the  concave  lenses  has  therefore 
added  to  the  muscle  disturbance  and  increased  the  esophoria. 

VERIFYING    THE    DIAGNOSIS 

Presumably  then  we  have  a  case  before  us  of  simple  myopia, 
but  we  must  hesitate  and  give  the  case  further  consideration  before 
we  can  accept  this  diagnosis  as  correct. 

In  the  first  place  the  symptoms  of  which  the  patient  complains 
do  not  indicate  myopia.  They  are  symptoms  of  asthenopia,  which, 
does  not  commonly_oc_cur  in  connection  with  myopia. 

In  the  second  place,  the  mu^e_mibalance  is  one  of  esophoria, 
which  is  usually  associated  with  a  hypermetropic  condition  of 
refraction,  and  besides  this  imbalance  is  aggravated  by  the  lenses 
which  the  patient  accepts. 

In  the  third  place,  hypermetropia  is  the  predominant  error  of 
refraction,  and  for  this  reason,  as  well  as  to  give  the  patient  the 
benefit  of  any  doubt  that  may  exist,  we  should  always  approach  a 
case  suspecting  hypermetropia  and  make  our  examinations  such  as 
to  discover  hypermetropia  if  possible,  and  not  to  abandon  this 
supposition  until  it  is  positively  proven  that  hypermetropia  is  not 
present. 

In  the  fourth  place,  when  the  refraction  seems  to  be  myopic, 
we  should  always  suspect  the  possibility  of  false  or  apparent 
myopia,  especially  in  a  young  person  like  this,  and  where  the 
symptoms_are  such  as  to  indicate  some  nervous  disturbance. 

In  the  fifth  place,  the  possibility  of  spasm  of  the  accommoaa- 

tion  should  always  be  kept  in  mind,  in  persons  under  middle  age, 

"and  especially  where  the  glasses  have  been  changed-irequently  as 

in  this  case,  with  but  little  satisfaction  after  the  several  changes. 

In  view  of  these  considerations  we  must  look  upon  the 
diagnosis  of  myopia  with  great  suspicion,  and  make  our  tests 
rather  with  a  view  of  uncovering  hypermetropia.      If  the  latter  is 


Spasm  of  Accommodation  193 

not  present  our  examination  can  do  the  patient  no  harm  ;  but  if 
present  in  a  latent  form  we  can  do  the  patient  much  good  by 
detecting  its  presence,  in  fact,  this  is  the  only  way  we  can  do  our 
whole  duty  conscientiously  for  the  patient's  welfare  and  our  own 
reputation. 

Inasmuch  as  the  two  eyes  are  so  nearly  alike,  we  will  test  them 
together  in  the  act  of  binocular  vision,  as  in  this  way  it  is  possible 
to  secure  better  results.  We  will  place  in  the  trial  frame  before  the 
patient's  eyes  a  pair  of  -I-4D.  lenses.  Before  she  has  an  oppor- 
tunity to  complain  that  she  cannot  see  through  them,  we  will  tell 
her  that  we  expect  the  glasses  to  blur  her  vision  very  much,  but 
that  we  use  them  to  accomplish  a  certain  purpose,  and  that  therefore 
we  will  ask  her  to  submit  to  their  inconvenience  for  a  little  while. 

You  gentlemen  will  of  course  understand  that  we  are  using 
these  somewhat  strong  convex  lenses  to  repress  the  accommodation, 
which  is  probably  unduly  active,  and  in  this  way  we  hope  to 
discover  the  real  condition  of  the  eye  which  may  be  very  different 
from  the  manifest  condition,  as  we  have  found  it.  In  order  to 
secure  the  relaxing  effect  of  these  convex  lenses  on  the  accommo- 
dation, we  will  allow  the  lady  to  wear  these  lenses  for  a  little  while, 
and  in  the  meantime  I  will  call  your  attention  to  a  few  facts  about 

SPASM    OF    ACCOMMODATION 

The  .constant  strain  on  the  ciliary  muscle  that  is  necessary  to 
afford  clear  vision  in  hypermetropic  conditions  of  refraction,  gives 
rise  to  spasm  of  the  accommodation,  which  is  simply  a  continued 
and  persistent  contraction  of  the  ciliary  muscle. 

Such  spasm  may  occur  in  any  condition  of  refraction,  even  in 
emmetropia,  which  is  then  transformed  into  an  apparent  myopia. 
When  it  occurs  in  hypermetropia,  the  defect  is  concealed  and  the 
eye  made  apparently  emmetropic,  or  the  contraction  of  the  muscle 
may  go  too  far  and  the  eye  made  apparently  myopic,  as  we  suspect 
in  the  case  before  us. 

A  simple  hypermetropic  astigmatism  by  this  means  is  trans- 
formed into  a  simple  myopic  astigmatism,  the  defective  meridian 
being  transposed  to  right  angles.  A  myopic  eye  is  made  still  more 
myopic. 

Spasm  of  the  accommodation  has  been  the  bug-a-boo  of  the 
optometrist,  because  it  is  so  difficult  to  detect  and  conquer  it  with- 
out a  mydriatic.     In  the  majority  of  cases,  if   the  causes  can  be 


194  Clinics  in  Optometry 

discovered  and  remedied,  the  spasm  will  gradually  disappear,  and 
the  expert  optometrist  will  be  able  to  accomplish  this  without  resort 
to  a  mydriatic. 

Spasm  of  accommodation  is  more  apt  to  occur  in  persons  of  a 
nervous  temperament,  and  strange  to  say  it  does  not  depend  upon 
the  vigor  of  the  accommodation  ;  that  is  to  say,  persons  with  a 
relatively  feeble  accommodation  may  suffer  from  cramp  of  the  ciliary 
muscle  more  than  persons  of  strong  muscular  development.  It  is 
usually  found  in  connection  with  a  weakened  accommodation,  and 
instead  of  being  an  evidence  of  strength,  must  be  regarded  as  an 
indication  of  nervous  debility. 

The  causes  of  accommodative  spasm  are  many  and  various. 
The  direct  cause  is  the  necessary  effort  of  the  ciliary  muscle  to 
overcome  a  hypermetropic  condition  of  refraction,  and  I  may  also 
mention  a  trial  of  sight  by  concave  lenses  as  a  contributing  cause. 

The  indirect  causes  are  a  neurotic  condition  of  the  patient,  a 
systematic  tendency  to  spasmodic  affections,  a  hyper-sensitive  retina, 
overwork  or  abuse  of  the  eyes  and  muscular  insufficiency. 

SYMPTOMS    OF    SPASM    OF    THE    ACCOMMODATION 

The  symptoms  of  accommodative  spasm  are  photophobia_(dread 
of  light),  lachrymation  (excessive  watering  of  eyes),  pains  or 
discomfort  of  some  kind,  contracted  pupils,  hyperemia  of  the 
conjunctiva,  impairment  of   distant  vision  and    simulated  myopia. 

A  certain  amount  of  spasm  of  accommodation  is  really  physio- 
logical and  is  due  to  the  normal  tone  of  the  ciliary  muscle.  The 
condition  of  rest  of  the  ciliary  muscle  is  not  one  of  complete 
relaxation,  as  in  a  state  of  paralysis.  The  tone  of  the  muscle  of 
accommodation  keeps  it  in  a  condition  of  mild  contraction. 

This  causes  a  slight  increase  in  the  refraction  of  the  eye, 
amounting  to  i  D.  or  more  in  childhood,  and  diminishing  to  .50  D. 
or  .  25  D.  in  middle  age.  Hence  even  in  eyes  apparently  emme- 
tropic when  atropine  is  used,  the  refraction  of  the  eye  is  slightly 
less  than  when  tested  in  its  normal  condition. 

It  is  only  when  the  ciliary  muscle  (which  may  be  said  to  be 
extremely  excitable)  exceeds  this  physiological  limit  and  keeps  up 
its  excessive  action  constantly,  that  we  have  the  condition  which 
we  are  considering  and  which  we  know  as  spasm  of  accommodation. 

In  testing  the  vision  of  a  patient  with  accommodative  spasm, 
you  will  be  likely  to  find  great  variability  in  the  acuteness  of  vision. 


Spasm  of  Accommodation  195 

At  first  he  may  say  he  can  only  see  the  larger  letters  at  the  top  of 
the  card,  then  the  smaller  letters  begin  to  come  into  view,  and  he 
reads  down  almost  to  the  20  line,  which  is  in  turn  again  blotted  out 
and  only  the  larger  letters  remain  legible.  The  varying  acuteness 
of  vision  is  dependent  upon  the  contraction  and  relaxation  of  the 
ciliary  muscle. 

Another  evidence  of  spasm  of  accommodation  is  a  variableness 
in  the  appearance  of  the  radiating  lines  on  the  clock-dial  card,  at 
one  time  patient  saying  one  set  of  lines  appear  clear  and  distinct, 
and  the  next  moment  they  become  dim  and  another  set  of  lines 
appear  plainer. 

In  simple  hypermetropic  astigmatis-m,  there  is  apt  to  be  spasm 
of  accommodation,  which  transposes  the  case  into  myopic  astigma- 
matism,  with  the  defective  meridian  changed  to  right  angles. 

In  hypermetropic  astigmatism  with  the  rule,  the  horizontal 
meridian  is  hypermetropic  and  the  vertical  meridian  emmetropic. 
The  ciliary  muscle  instinctively  comes  into  action,  neutralizing  the 
hypermetropia  in  the  horizontal  meridian  and  making  it  apparently 
emmetropic,  and  at  the  same  time  increasing  the  refraction  of  the 
vertical  meridian  to  an  equal  extent  and  making  it  apparently 
myopic.  In  this  way  the  defective  meridian  is  changed  from 
horizontal  to  vertical,  and  the  location  of  the  indistinct  lines  would 
vary  with  the  contraction  and  relaxation  of  the  accommodation. 

Another  evidence  of  accommodative  spasm  is  the  variation  in 
the  glasses  accepted  by  the  patient  at  different  examinations,  or 
perhaps  even  during  the  same  test. 

Corroborative  evidence  of  spasm  of  the  accommodation  is 
furnished  when  the  retinoscopic  findings  vary  greatly  from  the  test 
with  the  trial  case.  In  the  first  case  the  darkened  room  and  the 
request  to  patient  to  look  off  into  distance  without  fixing  the  sight 
on  any  one  object  in  particular,  presents  conditions  that  favor 
relaxation  of  any  spasm  of  the  ciliary  muscle  that  may  be  present. 

DIAGNOSIS   OF    SPASM 

,The  diagnosis  of  spasm  of  accommodation  can  be  made  in 
accordance  with  the  characteristics  I  have  outlined  to  you,  and 
corroborated  by  a  determination  of  the  real  refractive  condition  by 
persistent  and  patient  fogging,  or  in  extreme  cases  by  the  physician's 
aid  in  the  use  of  a  cycloplegic,  which  in  obstinate  cases  must  some- 
times be  used  for  several  days  or  a  week.     I  might  say  in  passing 


196  Clinics  in  Optometry 

that  if  atropine  is  used  the  proper  strength  is  four  grains  to  the 
ounce,  or  approximately  a  1  per  cent,  solution.  It  may  be  dropped 
into  the  eyes  two  or  three  times  a  day,  until  the  physiological  effect 
of  the  belladonna  becomes  apparent  in  the  flushed  face  and  the 
parched  throat. 

A  diagnostic  point  of  some  value  is  a  discrepancy  between  the 
position  of  the  far  point  and  the  degree  of  apparent  myopia  as 
shown  by  the  test  lenses. 

For  instance  the  far  point  may  be  thirteen  inches,  which  would 
indicate  a  myopia  of  3  D.  The  acuteness  of  vision  is  f#,  which  is 
easily  raised  to  normal  by  —  1  D.  With  such  a  marked  difference, 
you  would  at  once  suspect  accommodative  spasm. 

TREATMENT    OF    SPASM 

In  the  treatment  of  spasm  of  the  accommodation,  the  first  step 
is  to  discover  and  remove  the  cause,  but  I  must  acknowledge  that 
the  diagnosis  of  the  cause  of  the  spasmodic  action  is  not  always 
easily  made.  I  have  already  referred  to  the  causes  of  spasm,  and 
can  only  repeat  that  the  effort  to  overcome  a  refractive  error  is  the 
most  common  cause  ;  in  addition  to  this  it  may  be  dependent  upon 
an  insufficiency  of  convergence,  which  is  to  be  explained  as 
follows  :  the  excessive  effort  required  to  maintain  the  necessary 
convergence  excites  a  corresponding  effort  of  the  accommodation, 
on  account  of  the  close  relation  that  naturally  exists  between  the 
accommodation  and  convergence.  Under  such  circumstances  a  pair 
of  prisms  bases  in  would  assist  in  relaxing  the  ciliary  spasm  by 
removing  the  cause,  which  is  the  desire  for  excessive  effort  of  the 
internal  recti  muscles. 

If  the  eyes  have  been  overworked,  they  should  be  rested  if 
possible  for  a  few  days  before  the  examination  is  made,  during 
which  time  of  rest  light  smoke  glasses  may  be  worn  and  especially 
if  the  retina  is  hyper-sensitive. 

If  a  conjunctivitis  is  present  or  there  is  a  noticeable  nervous 
element  in  the  case,  the  services  of  a  physician  should  be  availed  of 
in  the  treatment  of  such  conditions,  in  order  to  place  the  eyes  in  a 
condition  more  favorable  for  examination. 

The  direct  repression  of  the  excessive  accommodation  is 
accomplished  by  means  of  convex  lenses,  a  moderately  strong  pair 
for  reading  and  a  weaker  pair  for  distance.  Of  course,  wearing 
convex  lenses  for  this   purpose   makes  vision   indistinct,    and  the 


Spasm  of  Accommodation  197 

patient  is  apt  to  rebel.  The  rationale  of  the  treatment  must  be 
explained  to  him,  and  in  cases  of  intelligent  persons  their  co-opera- 
tion can  be  secured.  Otherwise  the  distance  glasses  will  probably 
have  to  be  dispensed  with  and  reliance  placed  on  the  reading 
glasses,  to  which  few  persons  will  object. 

The  rule  as  set  forth  in  all  text  books  to  give  the  strongest 
convex  lens  with  which  patient  can  read  the  No.  20  line,  or  the 
weakest  concave  lens  that  affords  the  same  vision,  is  a  time-honored 
one,  and  shows  recognition  of  the  fact  that  it  is  always  desirable  to 
relieve  the  ciliary  muscle  or  impose  as  slight  a  tax  upon  it  as  possible. 

But  fogging  for  the  uncovering  of  latent  hypermetropia  is  of 
later  origin,  whether  it  be  used  temporarily  during  the  examination, 
or  more  permanently  by  prescribing  such  glasses  for  constant  wear, 
which  not  only  tend  to  check  ciliary  innervation,  but  also  probably 
by  dulling  the  vision  relieve  the  sight  centers  of  the  tax  which 
sharp  vision  entails.  In  some  parts  of  the  world  where  the 
atmosphere  is  humid  and  foggy  the  greater  part  of  the  time,  the 
statement  is  made  that  nervous  ailments  are  uncommon,  because  in 
a  hazy  atmosphere  the  visual  centers  are  not  taxed  to  the  same 
extent  as  in  a  clear  atmosphere.  Fogging  glasses  sometimes 
produce  a  state  of  quiet  and  rest  even  to  the  extent  of  sleep. 

We  will  now  return  to  our  patient  who  has  been  very  patiently 
waiting,  and  she  tells  us  the  glasses  are  not  so  uncomfortable  as  at 
first,  and  that  she  can  see  a  little  better.  On  directing  her  attention 
to  the  test  card,  she  is  barely  able  to  name  the  largest  letter  at  the 
top  of  the  card,  showing  a  vision  of  -££-$. 

We  cautiously  and  slowly  reduce  the  convex  lenses  by  concaves 
placed  in  front,  commencing  with  —  .50  D. ,  which  affords  an 
improvement,  and  increasing  .25  D.  at  a  time  until  —  2  D.  is 
reached,  when  the  No.  20  line  is  perfectly  clear  and  legible.  We 
therefore  in  this  case  have  uncovered  2  D.  of  hypermetropia. 

We  will  order  +  1.50  D.  for  constant  wear,  which  from  our 
experience  in  similar  cases,  we  feel  confident  will  afford  the  greatest 
relief  and  comfort,  if  the  lady  will  overlook  the  slight  annoyances 
she  may  feel  during  the  first  week,  and  persevere  in  their  use. 

This  case  then  is  one  of  apparent  or  accommodative  myopia  ; 
it  is  as  you  see  not  myopia  at  all,  but  it  has  been  made  to  simulate 
myopia  on  account  of  the  spasm  of  accommodation  which  has  been 
present  to  overcome  the  hypermetropia,  which  is  the  real  refractive 
condition  of   the   eye.      The   innervation    of    the   ciliary   muscles 


198  Clinics  in  Optometry 

becomes  excessive,  and  passes  beyond  that  point  where  it  would 
suffice  to  neutralize  the  diminished  refraction,  and  in  going  farther 
produces  the  simulated  myopia. 

I  hope  this  case  has  made  such  a  deep  impression  upon  your 
minds  that  you  will  carry  it  away  with  you,  and  that  the  lessons 
you  have  learned  from  it  will  be  of  value  to  you  in  your  daily 
practice. 

How  easily  concave  glasses  could  have  been  given  to  this  lady, 
and  how  injuriously  they  would  have  affected  her.  Always  be  on 
your  guard  in  your  patients  for  spasm  of  accommodation,  and 
always  be  slow  in  prescribing  concave  lenses.  Carry  this  piece  of 
advice  with  you  :  Suspect  every  case  to  be  hypermetropic,  until 
positively  proven  otherwise. 


Exophoria 


[Clinic  No.  31] 

This  little  patient  is  Master  A.  E.  K. ,  aged  nine.  His  mother 
tells  us  that  he  has  complained  of  headaches  ever  since  he  was  three 
years  of  age.  She  has  just  consulted  an  oculist  about  him,  who 
recommends  an  operation  as  the  only  method  of  treatment  that  will 
afford  relief.  She  objects  to  this,  however,  and  brings  the  child  to 
us  to  see  if  he  cannot  be  fitted  with  glasses  that  will  be  of  benefit 
to  him. 

We  find  the  acuteness  of  vision  of  each  eye  to  be  -§-§■  partly. 

We  turn  to  the  ophthalmometer,  which  shows  no  overlapping 
in  any  meridian,  proving  all  the  meridians  to  be  of  equal  curva- 
ture. Now,  inasmuch  as  the  normal  cornea  shows  a  slight  excess 
in  the  vertical  meridian  (about  .50  D.),  which  is  lacking  in  this  boy, 
we  must  class  this  case  as  one  of  astigmatism  against  the  rule,  that 
is,  about  .  50  D.  deficiency  in  the  vertical  meridian. 

Some  students  have  difficulty  in  understanding  how  astig- 
matism is  indicated  when  the  mires  maintain  the  same  relation  as 
the  ophthalmometer  is  rotated,  showing  neither  overlapping  nor 
separation  in  any  meridian.  To  their  minds  this  rather  indicates 
absence  of  astigmatism.  But  it  must  be  remembered,  and  this  is  an 
important  point,  that  normality  of  the  corneal  curvatures  is  not 
equality  in  all  meridians,  but  an  excess  of  .50  D.  in  the  vertical 
meridian.  If  now  the  vertical  meridian  is  on  an  equality  with  the 
horizontal,  when  it  should  exceed  it,  we  must  conclude  that  its 
refraction  is  deficient,  which  means  astigmatism  against  the  rule. 

If  the  ophthalmometer  shows  the  vertical  meridian  to  exceed 
the  horizontal  by  .  50  D. ,  we  say  no  astigmatism.  If  it  exceeds  by 
a  greater  amount  than  .50  D. ,  we  say  astigmatism  with  the  rule. 

We  next  make  a  retinoscopic  examination,  which  shows  the 
horizontal  meridian  to  be  emmetropic,  and  the  vertical  meridian  to 
be  hypermetropic  to  the  extent  of  .  50  D. 

The  retinoscope  and  the  ophthalmometer  agree,  and  we  have  a 
plain  case  as  far  as  the  condition  of  the  refraction  goes.  We  now 
turn  to  the  trial  case  to  see  if  the  subjective  examination  will 
verify  the   objective    examinations.      We   try  -f  .50  D.   spheres, 


200  Clinics  in  Optometry 

which  the  boy  does  not  like  very  much,  but  when  we  replace  them 
with  -f-  .50  D.  cyl.  axis  1800,  he  says  at  once,  the  last  are  the 
best  We  try  stronger  cylinders,  and  we  try  the  addition  of 
spheres,  but  both  are  rejected.  We  rotate  the  cylinder,  first 
one  way  and  then  the  other,  with  the  effect  of  making  vision  worse, 
showing  1800  to  be  the  proper  position  for  axis  of  cylinder.  We 
have  thus  verified  the  correction  of  the  refractive  error. 

In  the  regular  course  of  our  examination  we  come  now  to  look 
into  the  muscle  balance.  We  make  use  of  the  Maddox  rod  as  is 
our  usual  custom,  placing  it  over  the  left  eye.  We  explain  to  our 
little  patient  that  he  will  see  the  natural  light,  and  in  addition  he 
will  see  a  red  streak  of  light.  In  order  to  make  this  red  streak 
more  noticeable,  we  rotate  the  Maddox  rod,  and  by  this  means  he 
is  the  better  able  to  locate  the  streak.  He  tells  us  the  red  streak 
is  away  over  to  the  right.  This  means  crossed  diplopia  due  to 
exophoria.  This  is  to  be  corrected  by  prisms,  bases  in,  and  we 
try  prisms,  gradually  increasing  their  strength,  until  we  find  120 
are  required  to  bring  the  streak  and  the  light  together,  and  this 
then  represents  the  amount  of  the  exophoria.  The  muscle 
imbalance  is  the  essential  feature  of  this  case,  for  which  the  oculist 
previously  consulted  had  advised  an  operation.  It  will  be  profitable 
for  us  to  give  a  little  time  to-day  to  the  consideration  of  this  con- 
dition of  exophoria. 

Deficiency  of  convergence  may  be  latent,  as  in  the  present 
case,  when  we  call  it  exophoria,  or  it  may  be  manifest  when  it  is 
known  as  divergent  strabismus.  We  use  the  words  ' '  deficiency 
of  convergence"  advisedly,  as  implying  that  exophoria  in  most 
cases  is  to  be  regarded  as  a  lack  of  convergence  rather  than  an 
excess  of  divergence.  It  is  a  lessened  innervation  of  the  function 
of  esophoria,  where  there  is  convergence,  thus  contrasting  with  the 
conditions  present  in  an  excessive  innervation  of  the  convergence. 

SYMPTOMS    OF    EXOPHORIA 

Exophoria  is  the  condition  that  was  formerly  known  as 
"muscular  insufficiency,"  and  later  as  the  muscular  form  of 
asthenopia,  which  occurs  especially  when  the  eyes  are  tired  from 
prolonged  near  work  and  particularly  by  artificial  light. 

Headache  is  a  marked  symptom,  and  you  will  recall  that  this 
boy  has  suffered  from  headache  ever  since  he  was  three  years  of 
age.     This  headache  is  naturally  aggravated    by  close  use  of  the 


Exophoria  201 

eyes,  and  is  sometimes  accompanied  by  such  reflex  symptoms  as 
dizziness,  nausea,  vomiting  and  fainting.  Or  the  eyes  may  feel 
weak  and  tired,  the  words  "seem  to  jump,"  or  the  letters  "run 
together,"  sight  grow  dim  or  objects  appear  double  for  a  moment, 
without  the  customary  headache. 

Sometimes  near  work  must  be  abandoned  on  account  of  the 
disturbance  produced  by  over-taxation  of  the  internal  recti  muscles 
in  their  effort  to  maintain  convergence,  or  by  an  impossibility  to 
maintain  convergence  resulting  in  confused  vision  or  crossed  diplopia. 

CAUSES    OF    EXOPHORIA 

As  we  have  found  esophoria  in  the  majority  of  cases  to  be 
dependent  upon  hypermetropia,  so  on  the  other  hand  is  exophoria 
associated  with  a  myopic  condition  of  refraction,  and  for  the  same 
reasons.  In  the  first  case  the  accommodative  effort  required  to 
overcome  the  hypermetropia,  stimulates  the  convergence  to  extreme 
effort.  In  the  second  case,  the  myopic  eye  being  adapted  for  near 
vision,  requires  but  little  accommodative  impulse,  and  hence  the 
convergence  center  lacks  the  customary  stimulus,  thus  giving  rise 
to  an  insufficiency  of  convergence  or  exophoria. 

But  in  this  boy's  case  we  have  found  the  refraction  to  be 
slightly  hypermetropic  (and  astigmatic),  and  hence  we  must  look 
for  some  other  cause.  In  the  further  investigation  of  the  muscles, 
we  will  measure  the  power  of  the  convergence  and  of  the  diver- 
gence, which  is  accomplished  by  the  strongest  prisms  bases  out 
and  in  respectively  that  can  be  overcome. 

We  place  a  20  prism  base  in  before  the  right  eye,  while  we 
ask  the  boy  to  look  at  the  light  and  tell  us  if  he  sees  one  or  two. 
He  replies  that  he  sees  only  one.  We  place  another  2°  prism  base 
in  before  the  left  eye,  and  he  tells  us  that  he  still  sees  one  light. 
We  increase  first  one  prism  and  then  the  other  to  40,  and  still  the 
light  remains  single.  We  increase  one  prism  to  6°,  and  now  he 
says  he  sees  two  lights  ;  we  diminish  to  50  and  still  he  sees  two  ; 
we  return  to  40,  with  which  there  is  a  single  light.  We  have  now 
two  40  prisms  before  the  eyes,  which  represents  a  divergence 
power  of  8°,  which  is  the  full  normal  amount,  but  not  any  excess. 

We  now  place  a  prism  of  20  base  out  before  the  right  eye  ; 
this  at  first  causes  two  lights  to  be  seen,  but  they  quickly  fuse  into 
one.  We  place  a  20  prism  base  out  before  the  left  eye  ;  two  lights 
are  again  seen,  which  with  some  effort  are  fused  into  one.     We 


202  Clinics  in  Optometry 

increase  the  right  prism  to  40,  with  the  result  of  producing  a  diplopia 
which  the  boy  is  unable  to  overcome.  We  return  to  2°,  with  which 
the  light  remains  single.  We  have  now  20  prisms  before  each  eye, 
which  represents  a  convergence  power  of  only  40,  which  is  very 
much  below  the  normal  standard. 

In  this  case  then  the  exophoria  is  not  due  really  to  an  excess 
of  divergence,  but  to  a  very  great  diminution  of  convergence. 
There  is  only  a  seeming  excess  of  divergence  because  the  con- 
vergence is  so  much  below  the  standard.  The  external  recti 
muscles  are  relatively  strong,  but  not  absolutely  so. 

This  case  is  then  literally  one  of  ' '  insufficiency  of  the  internal 
recti,"  and  may  be  due  to  actual  weakness  of  these  muscles,  or 
inaction  of  these  muscles  because  of  imperfect  innervation.  In  a 
case  like  this  we  think  an  operation  is  contra-indicated  as  likely  to 
do  more  harm  than  good. 

When  you  have  charge  of  a  case  of  this  kind,  it  is  very 
difficult  to  determine  the  proper  proportion  that  should  be 
observed  between  rest  and  exercise,  in  giving  advice  as  to  the 
use  of  the  eyes.  It  only  seems  reasonable  that  rest  of  a  fatigued 
organ  would  afford  relief.  Inasmuch  as  it  is  impossible  to  close  the 
eyes  to  obtain  entire  rest,  we  do  the  next  best  thing  by  a  correction 
of  the  refraction,  which  affords  relief  to  the  ciliary  muscle,  and 
prisms  to  rest  the  extraocular  muscles.  Then  we  advise  our  patient 
that  near  use  of  the  eyes  must  be  discontinued  just  as  soon  as 
they  begin  to  feel  tired. 

DIAGNOSIS    OF    EXOPHORIA 

The  simplest  method  is  to  produce  an  artificial  vertical  diplopia 
by  means  of  a  prism  placed  base  up  or  down.  We  will  take  an  8° 
prism  and  place  it  before  this  boy's  right  eye  base  up,  while  we  ask 
him  to  look  at  the  light  across  the  room.  He  sees  two  lights,  one 
below  the  other.  We  know  the  lower  light  belongs  to  the  right 
eye,  because  a  prism  always  displaces  an  object  towards  its  apex. 
But  in  order  that  the  patient  may  distinguish  between  the  two 
lights  the  more  readily,  we  will  make  use  of  a  red  glass  over  the 
right  eye. 

The  image  formed  in  the  left  eye  is  the  natural  light,  and  that 
formed  in  the  right  eye  is  red.  We  ask  the  patient  if  he  sees  one 
natural  light  and  one  red  light,  and  which  light  is  above  and  which 
below.     He  replies  yes,  and  that  the  lower  light  is  the  red  one. 


Exophoria  203 

This  we  know  to  be  correct,  but  in  our  further  questions  we  must 
depend  upon  the  patient's  answers. 

"  Is  this  red  light  directly  below  the  white  light,  or  is  it  to  the 
right  or  left  ?  "   is  the  next  question. 

"  It  is  way  off  to  the  left." 

' '  About  how  far  to  the  left  ? ' ' 

Our  little  patient  seems  unable  to  answer  this  question,  but  he 
holds  his  hands  up  indicating  a  distance  between  them  of  about 
two  feet. 

This  then  is  a  case  of  crossed  diplopia,  which  we  know  must 
be  due  to  exophoria,  and  we  proceed  to  measure  the  amount  of 
same  by  determining  the  degree  of  prism  that  is  necessary  to  bring 
the  red  light  back  in  a  line  with  the  white  light.  This  we  finally 
find  to  be  120.     The  base  of  the  correcting  prism  is  in. 

As  I  stated  a  moment  ago  this  is  the  simplest  test,  but  it  is 
subject  to  one  disadvantage,  and  that  is  a  displacement  from  the 
yellow  spot  of  the  image  formed  in  the  right  eye  by  the  strong 
vertical  prism  placed  in  front  of  it. 

Usually  I  prefer  the  Maddox  rod  test.  You  are  all  familiar 
with  this  little  instrument.  The  one  I  hold  in  my  hand  is  a  mul- 
tiple rod,  being  a  series  of  parallel  cylinders  mounted  in  an  opaque 
diaphragm  of  suitable  size  to  be  placed  in  a  trial  frame.  These 
cylinders  produce  a  marked  elongation  of  images  in  a  direction  at 
right  angles  to  their  axes.  A  small  flame  seen  through  this  mul- 
tiple rod  appears  as  a  long  red  streak  of  light. 

In  testing  the  muscles  to  detect  the  presence  of  exophoria, 
the  rod  is  placed  in  the  trial  frame  in  a  horizontal  position,  in 
order  to  produce  a  vertical  streak  of  light.  The  patient  receives 
the  image  of  the  streak  in  one  eye,  and  of  the  uncovered  light  in 
the  other,  and  on  account  of  the  dissimilarity  in  the  shape,  size  and 
appearance  of  the  two  retinal  images,  it  is  impossible,  in  fact, 
nature  makes  but  little  effort  to  fuse  them,  and  in  abandoning  the 
attempt  to  produce  fusion,  the  eyes  are  free  to  assume  their 
position  of  equilibrium,  and  in  this  way  any  tendency  to  deviation 
which  has  been  latent  now  becomes  manifest. 

We  place  this  Maddox  rod  over  the  boy's  right  eye,  and  in 
answer  to  our  question  he  says  the  red  streak  is  considerably  to 
the  left  of  the  light.  A  prism  base  in  brings  it  closer,  and  after  a 
few  trials  we  find  that  a  130  prism  causes  the  streak  to  pass  ver- 
tically through  the  flame. 


204  Clinics  in  Optometry 

This  result  does  not  exactly  correspond  with  the  former  test, 
but  we  must  expect  some  variation  from  the  several  tests,  or  even 
from  the  same  test  repeated  at  different  times. 

Now,  it  is  a  well-known  fact  that  when  exophoria  exists  _at 
twenty  feet,  it  is  of  higher  degree  at  the  reading  distance^  And 
even  in  some  cases  which  show  slight  esophoria  at  distance,  there 
will  be  exophoria  at  the  reading  point.  This  is  due  to  the  fact  that 
exophoria,  being  caused  by  an  insufficiency  of  the  internal  recti 
muscles,  will  show  of  higher  degree  at  the  reading  distance  where 
the  tax  on  the  insufficient  muscles  is  greatest.  This  is  called 
exophoria  in  accommodation,  which  term  is  used  to  denote  the 
insufficiency  found  at  the  reading  point,  in  contrast  with  the 
simple  word  exophoria,  which  indicates  the  imbalance  at  a  distance. 

We  will  bring  this  boy's  chair  close  up  to  the  light,  and  repeat 
the  test  in  order  to  determine  the  amount  of  exophoria  in  accom- 
modation. We  place  the  Maddox  rod  in  the  same  position,  and 
the  boy  sees  the  red  streak  to  the  left,  and  we  find  a  200  prism 
base  in  is  required  to  bring  the  streak  back  to  the  light.  This 
serves  to  emphasize  the  weakness  of  the  internal  recti  muscles  that 
is  present  in  this  case. 

TREATMENT    OF    EXOPHORIA 

1.  Correction  0/  Refraction.  As  ametropia  is  regarded  as 
being  the  most  common  cause  of  muscular  insufficiency,  it  is  obvious 
that  the  first,  step  in  the  treatment  of  such  insufficiency  should  be 
the  correction  of  any  existing  error  of  refraction.  Sometimes  such 
lenses  will  suffice  to  restore  a  proper  muscle  balance  ;  but  at  any 
rate  they  remove  a  disturbing  factor  which  would  otherwise  stand 
in  the  way  of  a  cure. 

In  this  boy's  case  we  will  order  the  weak  convex  cylinders 
which  we  found  in  the  early  part  of  our  examination.  If  his  eyes 
were  myopic,  as  is  usually  the  case  in  exophoria,  for  the  reasons 
already  explained,  we  would  order  the  correcting  lenses  alone  in 
the  expectation  that  they  would  beneficially  affect  the  convergence  ; 
but  we  can  hardly  look  for  any  such  improvement  from  these  weak 
convex  cylinders,  and  hence  we  must  use  prisms  in  the  treatment 
of  this  case. 

2.  Prismatic  lenses.  Prisms  are  often  necessary  for  the  relief 
of  exophoric  asthenopia,  within  the  limitations  to  which  this  form 
of  lenses  is  restricted.     The  prism  is  placed  in  such  position  as  to 


Exophoria  205 

afford  assistance  to  the  weakened  and  strained  convergence,  which 
in  these  cases  would  be  base  in. 

Exophoria  is  almost  invariably  greater  at  the  reading  distance 
than  at  twenty  feet,  as  we  have  seen  in  this  case,  and  for  this 
reason  one  strength  of  prisms  will  not  jilways  suffice  fojr  constant 
wear  for  all  purposes.  Sometimes  where  the  asthenopia  is  noticed 
only  after  prolonged  near  work,  it  may  suffice  to  wear  the  prisms 
only  in  close  use  of  the  eyes  ;  but  if  the  exophoria  is  of  high 
degree,  relief  can  only  be  obtained  by  the  constant  wearing  of 
prisms,  in  which  cases  stronger  prisms  may  be  necessary  for  pro- 
longed close  use.  The  strength  of  the  prism  to  be  prescribed  is 
always  an  open  question,  that  must  be  decided  by  a  consideration  of 
each  case  individually.  It  is  never  proper  to  give  prisms  strong 
enough  to  correct  the  full  amount  of  the  exophoria,  but  as  a 
general  rule  I  would  say  about  one-half  the  correction  should  be 
given,  which  in  exceptional  cases  may  be  increased  to  two-thirds. 

Some  authorities  claim  that  prisms  for  constant  wear  do  more 
harm  than  good,  by  increasing  the  difficulty  and  requiring  stronger 
and  stronger  prisms.  I  cannot  agree  with  these  views,  because  by 
such  use  of  prisms  we  relieve  the  great  strain  upon  the  conver- 
gence, which  function  is  then  called  upon  to  perform  only  so  much 
work  as  it  can  comfortably  do,  and  in  this  way  is  placed  in  a  posi- 
tion to  regain  its  lost  strength  or  even  develop  more  power. 

I  will  write  on  the  blackboard  the  prescription  I  will  order  for 
this  boy  :  O.  U.+  .50  D.  cyl.  axis  1800  Q  prism  30  base  in.  This 
represents  a  total  prismatic  value  of  6°,  which  is  just  one-half  the 
amount  of  the  exophoria  manifest  at  twenty  feet.  In  a  boy  as 
young  as  this,  we  can  scarcely  order  stronger  prisms  for  reading  on 
account  of  the  inconvenience  of  two  pairs  of  glasses. 

Prism  Exercises.  I  do  not  feel  that  I  can  close  the  clinic 
without  giving  you  a  few  directions  on  prism  exercises  to  develop 
the  strength  of  the  convergence.  The  prisms  are  placed  bases  out, 
and  the  strongest  pair  is  found  with  which  singleness  of  vision  with 
the  distant  light  can  be  maintained.  These-  are  set  in  a  frame  and 
worn  for  five  or  ten  minutes,  being  lifted  about  every  thirty  seconds. 
This  exercise  may  be  repeated  daily,  the  effort  being  made  to 
increase  the  prisms  each  day.  Very  weak  prisms  will  be  neces- 
sary to  start  with,  and  the  exercises  should  be  continued  until  the 
power  of  adduction  has  reached  200  at  least  ;  in  some  cases  it  may 
not  be  difficult  to  reach  40  or  500. 


2o6  Clitiics  in  Optometry 

These  exercises  you  will  have  to  conduct  yourself  in  your 
office,  but  in  addition  you  may  give  your  patient  for  home  use 
weak  prisms  set  with  bases  out.  They  should  not  be  too  strong 
and  they  may  be  worn  for  an  hour  or  two  (continuously  or  at 
intervals,  as  the  eyes  best  stand  them)  every  day  as  the  person  is 
doing  his  daily  work. 

These  exercises  may  be  varied  as  follows:  a  pair  of  weak 
prisms  such  as  can  be  easily  evercomje  is  placed^  on  the  patients 
eyes  bases  put,  while  he  is  standing  two  feet  from  the  light.  He  is 
requested  to  recede  from  the  light  slowly  while  keeping  his  eyes 
fixed  upon  it.  If  diplopia  shows  itself  at  any  distance,  he  is  to 
return  to  his  original  position  and  recede  again  until  he  can  get  to 
twenty  feet  without  diplopia.  The  exercise  may  then  be  repeated 
with  slightly  stronger  prisms,  and  then  finally  he  remains  at  twenty 
feet  and  raises  and  lowers  the  prisms  while  gazing  at  the  light,  as 
previously  directed. 

In  addition  to  these  prism  exercises,  the  patient  may  carry  out 
systematic  exercises  of  the  muscles  (called  ocular  gymnastics), 
somewhat  as  follows  : 

Tell  the  patient  to  look  intently  at  the  point  of  a  pencil  held 
at  arm's  length,  and  then  slowly  bring  the  same  closer  to  the  eyes. 
If  the  pencil  becomes  double,  it  should  be  pushed  away  and  the 
exercise  repeated  from  the  original  distance.  This  procedure  is  one 
that  has  the  merit  of  convenience,  as  it  can  be  practiced  at  any 
time  or  place  and  requires  no  apparatus. 


Transposition  of  Lenses  as  Illustrated  by  a  Case  of 
Mixed  Astigmatism 

[Clinic  No.  32] 

E.  M.  G. ,  aged  forty-eight  years,  a  professional  man. 
Complains  of  some  difficulty  in  both  distant  and  near  vision,  also 
more  or  less  discomfort  in  head  and  eyes.  Has  worn  glasses 
for  the  last  twenty-five  years,  but  as  they  have  not  been  changed 
for  four  years,  he  feels  they  are  no  longer  suitable. 

We  find  his  acuteness  of  vision  is  ff  partly,  and  the  same 
for  each  eye. 

We  turn  to  our  trusted  ophthalmometer,  the  readings  of  which 
show  an  overlapping  of  2.50  D.  in  the  horizontal  meridians.  For 
reasons  which  have  already  been  explained  to  you  at  former  clinics, 
this  case  proves  to  be  one  of  astigmatism  against  the  rule,  and 
making  allowance  for  the  proper  additions,  the  amount  of  astigma- 
tism is  3  D. ,  the  excess  of  curvature  being  in  the  horizontal 
meridian. 

We  take  up  the  trial  case  examination  next,  and  commence 
with  a  +  1  D.  cylinder,  which  according  to  the  indications  of  the 
ophthalmometer,  we  place  with  axis  at  1800.  This  causes  an  im- 
provement in  vision,  and  the  next  line  now  becomes  readable.  We 
try  to  increase  the  strength  of  the  cylinder,  but  without  success. 

As  we  have  apparently  corrected  one  meridian,  and  as  the 
ophthalmometer  shows  a  still  greater  amount  of  astigmatism,  we 
suspect  it  must  be  in  the  other  meridian,  and  leaving  the  convex 
cylinder  in  place  we  add  to  it  a  concave  cylinder  with  axis  at 
right  angles.  We  commence  with  a  —  .25  D.  cyl.  axis  900, 
which  affords  a  noticeable  improvement  in  vision,  and  increase 
25  D.  at  a  time,  each  change  of  lenses  producing  still  clearer 
vision.  When  we  reach  a  —  1  D.  cylinder,  the  patient  is  able 
to  quickly  name  all  the  letters  on  the  No.  20  line.  We  test  the 
other  eye  and   find  exactly  the  same  correction. 

This  then  is  a  case  of  mixed  astigmatism  against  the  rule, 
the  degree  of  defect  being  represented  by  the  following  cross 
cylinder  : 

-f-  1  D.  cyl.  axis  1800  Q  —  1  D.  cyl.  axis  900, 


208  Clinics  in  Optometry 

This  gentleman  complains  that  he  has  considerable  difficulty 
in  the  close  use  of  his  eyes,  and  that  reading  has  lost  all  attraction 
for  him  ;  and  no  wonder,  for  he  has  already  reached  the  presbyopic 
age,  and  the  glasses  that  correct  his  error  of  refraction  no  longer 
suffice  to  afford  the  necessary  help  in  close  use  of  the  eyes. 

We  place  these  cross  cylinders  in  the  trial  frame,  and  hand  the 
reading  test  card.  He  holds  it  at  arms'  length,  and  even  then  he 
can  scarcely  make  out  the  smaller  size  print.  At  this  age  (forty- 
eight  years)  we  usually  expect  to  find  from  i  D.  to  1.50  D.  of 
presbyopia,  and  we  will  therefore  add  a  +  1  D.  lens  to  the  cross- 
cylinders.  This  produces  a  marked  improvement  in  reading  vision, 
and  makes  the  type  sharp  and  clear  at  the  customary  distance. 

We  will  of  course  make  a  test  of  the  muscle  balance,  and 
finish  up  with  an  examination  by  the  ophthalmoscope  and  retino- 
scope,  but  we  will  not  dwell  on  these  matters  to-day,  as  our  special 
interest  in  this  case  lies  in  the  transposition  of  lenses  involved  in 
these  prescriptions. 

TRANSPOSITION   OF    LENSES 

Transposition  means  a  change  in  the  curvatures  of  a  lens  with- 
out affecting  its  refractive  value,  and  is  a  matter  of  mathematical 
calculation  as  well  as  algebraic  addition.  Preference  is  usually 
given  to  the  simpler  and  less  expensive  form  of  lens,  and  therefore 
when  an  optometric  examination  results  in  a  cross-cylinder  as  in 
this  case,  it  is  customary  to  transpose  the  formula  to  a  sphero-cyl- 
inder  before  sending  the  prescription  to  the  manufacturing  optician. 

This  formula  is  one  in  which  the  two  cylinders  are  of  dissimilar 
signs  and  with  their  axes  at  right  angles  to  each  other.  In  such 
cases  the  rule  is  as  follows  :  Take  either  one  of  the  cylinders  for 
the  sphere  of  the  new  combination,  retaining  its  sign  ;  make  the 
^cylinder  of  the  new  combination  from  the  sum  of  the  two  former^ 
cylinders,  using  the  sign  and  axis  of  that  cylinder  which  was  not 
used  for  the  sphere. 

Let  me  write  the  formula  on  the  blackboard  and  then  proceed 
to  transpose  it  before  your  eyes  so  that  you  can  follow  me  : 

4-  1  D.  cyl.  axis  1800  Q  —  J  D-  cy1-  axis  9°°. 

We  will  take  the  first-named  cylinder  for  our  sphere,  retaining 
its  sign  ;  this  gives  us  -f  1  D.  S. 

Then' we  will  take  the  sum  of  the  two  cylinders  for  our  new 
cylinder.     Now  you   will   please  note  the  words   I   use,   viz. ,   the 


Transposition  of  Lenses  in  a  Case  of  Mixed  Astigmatism  209 

sum  of  the  two  cylinders,  which  in  this  case  would  be  :  1  and  1  =  2. 
I  do  not  say  the  addition  of  the  two  cylinders,  because  the  algebraic 
addition  of  +  1  and  —  1  would  equal  nothing. 

But  instead  it  is  really  algebraic  subtraction,  which  is  the  pro- 
cess of  finding  the  difference  between  two  numbers,  or  to  express 
it  in  other  words,  the  number  of  units  which  lie  between  the  two 
numbers. 

Now  in  this  formula  under  consideration,  the  plus  number  rep- 
resents a  unit  on  the  positive  side  of  zero,  and  the  minus  a  unit  on 
the  negative  side  of  zero,  and  the  difference  between  them  is  two 
units. 

Where  the  numbers  to  be  subtracted  have  dissimilar  signs, 
that  is,  where  one  is  plus  and  the  other  minus,  then  the  subtraction 
really  means  addition  in  accordance  with  the  following  rules  : 

When  a  positive  number  is  to  be  subtracted  from  a  negative 
number,  we  change  the  sign  to  minus  and  proceed  as  in  addition, 
and  the  result  is  a  minus  number. 

When  a  minus  number  is  to  be  subtracted  from  a  positive,  we 
change  the  sign  to  plus  and  proceed  as  in  addition,  the  result 
being  a  positive  number. 

For  those  members  of  the  class  who  have  never  studied  alge- 
bra, these  few  remarks  on  algebraic  subtraction  will  prove  of  value, 
not  only  in  this  case,  but  many  times  when  a  transposition  becomes 
necessary  or  desirable. 

Now  to  return  to  the  formula  under  consideration,  we  already 
have  the  sphere  of  the  new  sphero-cylindrical  combination,  and  we 
obtain  the  cylinder  by  subtracting  the  first  cylinder  from  the  second, 
according  to  the  rule  I  have  already  given  you,  and  the  result 
which  I  will  mark  on  the  blackboard  will  be  as  follows  : 

Subtract  -f-   1  from  —  1  =  —  2. 

I  will  repeat  the  rule  again  so  as  to  fix  it  in  your  memory  : 
change  the  sign  of  the  subtrahend  (the  number  to  be  subtracted) 
and  proceed  as  in  addition. 

We  have  now  for  the  new  formula  -f  1  D.  S.  C  —  2D.  cyl. , 
and  of  course  the  new  minus  cylinder  retains  the  axis  of  the  old 
minus  cylinder,  which  in  this  case  is  900. 

There  is  a  second  transposition  we  can  make  according  to  the 
same  rule,  as  follows  :  this  time  we  will  take  the  minus  cylinder  for 
our  sphere  ( —  1  D.  S.),  and  then  we  subtract  this  —  1  from  +  j, 


2io  Clinics  in  Optometry 

which  equals  -f  2,  retaining  of  course  the  original  axis  of  the  con- 
vex cylinder,  the  result  being  as  follows  :  —  1  D.  S.  Q  -f  2  D. 
cyl.  axis  1800. 

Now  if  you  will  look  on  the  blackboard  you  will  see  the  origi- 
nal cross-cylinder  and  the  two  sphero-cylindrical  transpositions 
made  from  it. 

+  1  D.  cyl.  axis  1800  Q  —  1  D.  cyl.  axis  900 
+  1  D.  S.  O  —  2  D.  cyl.  axis  900 
—  1  D.  S.  O  -f  2  D.  cyl.  axis  1800 

These  three  formulae  are  all  inter-transposable,  and  they  all 
have  the  same  optical  value  and  the  same  effect  on  the  rays  of 
light  passing  through  them.  Such  being  the  case  the  question  may 
occur  to  you,  which  one  is  preferable  ? 

It  is  seldom  that  a  cross-cylinder  is  ordered  ;  it  is  customary 
to  transpose  it  into  a  sphero-cylinder,  and  of  the  two  sphero-cylin- 
ders  into  which  this  cross-cylinder  is  transposable,  the  first  is  the 
one  to  be  preferred,  and  why  ? 

Now  you  understand  that  the  axis  of  a  cylinder  is  plane  glass, 
the  refractive  power  being  in  the  meridian  at  right  angles,  where 
the  effect  is  the  same  as  a  sphere  of  like  power. 

Now  you  also  understand  that  when  we  look  through  a  sphere 
at  any  place  except  its  optical  center,  a  prismatic  effect  is  produced. 

And  you  will  further  remember  from  your  studies  of  the  extra- 
ocular muscular  system  that  the  vertical  muscles  are  more  easily 
disturbed  and  thrown  out  of  balance  than  the  stronger  horizontal 
muscles. 

Now  bearing  these  three  facts  in  mind,  let  us  consider  the 
advantages  and  disadvantages  of   these  two  sphero-cylinders. 

In  the  first  one  the  axis  is  at  900,  and  therefore  there  is  noth- 
ing to  disturb  the  vertical  muscles,  while  the  slight  prismatic  effect 
produced  as  the  eyes  are  turned  from  side  to  side  is  easily  taken 
care  of  by  the  external  and  internal  recti. 

In  the  second  sphero-cylinder  the  axis  is  at  1800,  which  tfirows 
the  refractive  power  of  the  cylinder  in  the  vertical  meridian,  pro- 
ducing a  prismatic  effect  as  the  eyes  are  turned  down  (and  are  we 
not  constantly  turning  our  eyes  downward  more  or  less),  and  in 
this  way  disturbing  the  balance  of  the  vertical  muscles,  which  are 
relatively  weak  and  but  little  able  to  overcome  the  prismatic  effect 
without  showing  signs  of  asthenopia.      Therefore  you  can  under- 


Transposition  of  Lenses  in  a  Case  of  Mixed  Astigmatism  211 

stand  the  advantages   of  the  first  sphero-cylinder,    which   imposes 
no  strain  on  the  vertical  muscles. 

One  of  the  gentlemen  tells  me  he  cannot  clearly  comprehend 
the  reason  of  the  transpositions  I  have  given  you  or  why  the  given 
results  are  obtained,  and  as  there  may  be  others  who  are  a  little  at 
sea  on  the  matter,  I  will  give  you  a  further  explanation,  by  means 
of  diagrams  on  the  blackboard. 

+  1 


In  the  cross  cylinder  there  was  plus  one  power  in  the  vertical 
meridian  and  minus  one  power  in  the  horizontal,  always  remember- 
ing that  the  power  lies  at  right  angles  to  the  axis,  and  any  trans- 
positions that  are  made  must  strictly  retain  the  same  powers  in 
each  meridian. 

+  1  -  1 

+  2 


+  1 


+  1 


In  the  first  sphero-cylinder  there  is  a  +  1  D.  sphere,  which 
gives  its  power  in  both  meridians,  and  which  I  will  mark  on  the 
diagram.  Then  we  have  a  —  2D.  cylinder  with  its  axis  at  90°, 
and  its  refractive  power  lying  at  1800.  Now  then  a  -f-  1  placed 
against  a  —  2,  according  to  algebraic  addition  yields  a  —  1.  A 
comparison  with  the  first  diagram  shows  we  have  the  same  values 
in  each  meridian  in  this  sphero-cylinder. 

In  the  second  sphero-cylinder  there  is  a  —  1  D.  sphere  which 
gives  a  —  1  value  in  both  meridians  as  marked  on  the  diagram. 
Then  we  have  a  +  2  D.  cylinder  with  axis  at  1800  and  refractive 


212  Clinics  in  Optometry 

power  at  900.  The  addition  of  a  —  1  and  a  -f-  2  algebraically 
equals  +1.  A  comparison  of  this  diagram  with  the  other  two 
diagrams  shows  the  same  power  in  both  meridians  in  all  three  cases. 
For  the  reasons  mentioned  we  will  order  the  first-named 
sphero-cylinder  for  constant  wear,  and  for  reading  -f  1  D.  sphere 
to  be  added.  I  will  write  the  formula  on  the  blackboard  so  that 
you  can  all  follow  me. 

+  1  D.  S.  O  —  2  D.  cyl.  axis  900. 
+  1  D.  S.  added 


-f  2  D.  S.  O  —  2D.  cyl.  axis  90° 


We  tell  the  patient  he  can  have  his  glasses  made  in  bifocal 
form,  otherwise  he  must  have  two  pairs.  He  says  that  he  does  not 
like  bifocals  and  that  he  prefers  to  have  two  pairs  of  glasses.  His 
reading  correction  then  will  be  as  I  have  marked  on  the  board,  a 
+  2  D.  sphere  combined  with  a  —  2D.  cylinder. 

This  presents  another  opportunity  for  transposition  in  order  to 
reduce  this  formula  to  its  simplest  form.  The  —  2D.  cylinder 
neutralizes  the  +  2  D.  sphere  in  one  meridian,  and  leaves  +  2  D. 
value  in  the  meridian  at  right  angles.  In  other  words  we  may  say 
that  when  the  sphere  and  cylinder  are  of  like  amount  with  dis- 
similar signs,  they  equal  a  plane  cylinder. 


+  2 
—  2 


Perhaps  I  can  make  my  meaning  clearer  by  a  diagram  on  the 
blackboard.  The  +  2  D.  sphere  gives  a  +  2  D.  power,  in  both 
horizontal  and  vertical  meridians.  The  —  2D.  cyl.  with  axis 
at  900  gives  a  —  2D.  power  in  the  horizontal  meridian  and  piano  in 
the  vertical  meridian.  As  you  see  the  addition  of  +  2  and  —  2 
in  the  horizontal  meridian  yields  nothing,  or  in  other  words,  the 
one  neutralizes  the  other  in  this  meridian,  while  the  +  2  D.  power 
is  left  unaffected  in  the  vertical  meridian.  Therefore  the  proper 
transposition  for  reading  would  be  -f-  2  D.  cyl.  axis  1800. 


Transposition  of  Lenses  in  a  Case  of  Mixed  Astigmatism  2 1 3 

For  sake  of  verification  we  may  vary  the  presentation  of  the 
problem  as  follows  : 

•f  2D.  vertical  +  2  D.  horizontal 

o  -2D.  " 

+  2  D.  vertical  o 

the  result  being  exactly  the  same. 

While  I  am  on  this  subject  of  transposition,  let  me  give  you 
the  rule  for  the  transposition  of  a  sphero-cylinder,  according  to 
which  any  sphero-cylinder  can  be  transposed. 

The  sphere  is  obtained  by  the  algebraic  addition  of  the  sphere 
and  cylinder. 

The  cylinder  is  retained  as  in  the  orignal  except  that  its  sign 
and  axis  is  changed. 

In  order  to  illustrate  this  rule  I  will  write  the  formula  of  a 
sphero-cylinder  on  the  blackboard,  and  then  proceed  to  transpose 
according  to  this  rule. 

+  1  D.  S.  C  +  .50  D.  cyl.  axis  90°. 
-f-    .50  D.  change  sign  and  axis 

-f  1.50D.  S.  O  —  .50D.  cyl.  axis.  1800. 

Here  we  have  a  +  1  D.  sphere  and  a  +  .  50  D.  cylinder  with 
axis  at  900.  For  the  new  sphere  we  add  the  sphere  and  cylinder 
together,  and  as  both  have  plus  signs  the  result  is  -f  1.50  D. 
For  the  cylinder  we  change  the  sign  from  +  to  — ,  and  the  axis 
from  900  to  1800,  the  resultant  sphero-cylinder  being  shown  on 
the  blackboard. 

Now  we  will  take  this  same  sphero-cylinder  and  change  it 
back  again  as  follows  : 

-f  1.50  D.  S.  C  —  .50  D.  cyl.  axis  1800 
—    .50  D.  change  sign  and  axis 

+  i~D.  S.  C  +  -50  D.  cyl.  axis  900 

In  this  case  the  addition  of  the  +  1.50  D.  and  the  —  .50  D. 
equals  +  1  D.  as  the  new  sphere,  and  we  change  the  sign  from 
—  to  +,  and  the  axis  from  1800  to  900,  as  shown  on  the  blackboard. 

Now  we  will  take  the  reading  formula  for  this  gentleman, 
and  transpose  according  to  this  rule. 

+  2  D.  S.  C  —  2  D.  cyl.  axis  900 
—  2D.  change  sign  and  axis 

o  -f-  2  D.  cyl.  axis  1800 


214  Clinics  in  Optometry 

In  this  case  the  algebraic  addition  of  -f-  2  D.  and  —  2D. 
equals  nothing  and  leaves  us  without  a  sphere.  Change  the  sign 
from  —  to  +  and  the  axis  from  900  to  1800,  and  we  have  this 
simple  cylinder  as  the  result  of  the  transposition. 

If  we  wished  to  change  this  simple  cylinder  to  a  sphero-cylin- 
der,  we  can  do  it  by  the  same  rule  of  transposition  as  follows  : 

o  S.   C  +   2  D.   cyl.   axis   1800 
-f  2D.  change  sign  and  axis 


-f  2  D.  S.   O  —  2D.   cyl.   axis  900 

For  the  new  sphere  we  add  sphere  and  cylinder  together, 
which  is  simply  adding  nothing  to  2  D. ,  and  the  result  is  +  2  D. 
tor  the  sphere,  while  we  change  the  sign  and  axis  from  +  to  — , 
and  from  1800  to  90.  ° 

I  have  now  given  you  the  two  chief  rules  of  transposition, 
viz.,  the  transposition  of  a  cross-cylinder  into  a  sphero-cylinder, 
and  the  transposition  of  a  shero-cylinder  into  another  form  of 
sphero-cylinder.  And  this  case  is  interesting  as  illustrating  both 
these  rules  and  affording  a  practical  application  of  them. 

If  this  gentleman  had  been  willing  to  wear  bifocals,  we 
would  simply  have  ordered  +  1  D.  S.  segments  added  to  his 
distance  lenses. 

In  leaving  this  subject  it  will  be  interesting  to  state  that  a 
sphere  may  be  considered  as  composed  of  two  cylinders  of  the 
same  sign  and  power  with  axes  at  right  angles  ;  and  conversely 
any  two  cylinders  of  the  same  sign  and  power  with  axes  at  right 
angles,  are  equal  to  a  sphere  of  the  same  sign  and  power,  as  for 
example  : 

+  1  D.  S.  =  +  1  D.  cyl.  axis  900  Q  +  1  D.  cyl.  axis  1800 
+  1  D.  cyl.  axis  900  Q  +  1  D.  cyl.  axis  1800  =  +  1  D.  S. 

In  other  words  we  consider  the  refractive  power  of  the  two 
chief  meridians,  and  this  shows  the  power  of  the  whole  lens. 


Adjustment  of  Spectacles 


.    [Clinic  No.  33] 

Mr.  C.  H.  R.,  aged  fifty  years,  complains  of  difficulty  in 
reading  and  close  work.  In  answer  to  our  question  he  says  he  has 
never  worn  glasses. 

On  directing  his  attention  to  the  test  card  hanging  across  the 
room,  he  names  every  letter  on  the  No.  20  line,  showing  his  acute- 
ness  of  vision  to  be  f£  or  normal.  This,  of  course,  excludes 
myopia,  but  there  may  be  hypermetropia  or  a  slight  degree  of 
hypermetropic  astimatism. 

In  order  to  determine  the  probability  of  the  presence  of  the 
latter,  we  turn  to  our  ophthalmometer,  which  shows  only  the  usual 
amount  of  overlapping  in  the  vertical  meridian. 

We  now  make  the  test-case  examination  and  place  a  pair  of 
-f-  1  D.  lenses  before  the  eyes,  with  which  vision  still  remains  ■§£. 
We  increase  these  lenses  to  -J-  1.50  D.,  with  which  vision  is 
slightly  blurred  and  the  letters  on  the  same  line  are  named  with 
difficulty.  We  place  a  pair  of  —  .25  D.  before  these  +  1.50  D. 
and  now  the  letters  are  clear  and  the  line  is  easily  read.  This 
proves  the  presence  of  hypermetropia  to  the  amount  of  1.25  D. 

We  hand  patient  the  reading  card  and  find  that  he  is  unable  to 
read  any  of  the  smaller  type,  and  for  the  larger  type,  which  he  is 
able  to  see,  his  near  point  is  twelve  inches. 

This  man,  then,  is  a  hypermetrope,  and  as  he  has  reached  the 
age  of  fifty,  he  is,  in  addition,  a  presbyope.  The  wonder  is  that  he 
should  have  reached  this  age  without  having  felt  the  imperative 
need  of  glasses.  No  doubt  he  did,  but  he  ignored  the  demands  of 
nature,  but  inevitably  at  the  expense  of  a  great  strain  on  his  eyes. 

This  is  a  matter  of  common  observation  :  it  seems  natural  for 
people  to  postpone  the  wearing  of  glasses  as  long  as  possible,  and 
especially  do  presbyopes.  But  it  is  useless  and  foolish  to  fight 
against  nature  ;  rather,  it  is  a  part  of  wisdom  to  yield  easily  and 
save  the  eyes  the  great  burden  of  strain  otherwise  imposed  upon 
them. 

Our  patient  wants  glasses  only  for  reading,  which  we  will  figure 
out  according  to  the  presbyopic  rule  as  follows  : 


2i6  Clinics  in  Optometry 

Subtract  the  lens  representing  the  receded  near  point  from  the 
lens  representing  the  desired  near  point,  and  the  result  will  be  lens 
required  to  correct  the  presbyopia  and  restore  the  receded  near 
point  to  the  normal  distance. 

We  usually  select  the  smaller  size  type  to  determine  the  near 
point,  and  where  such  type  cannot  be  read  without  glasses,  we 
supply  a  known  convex  lens  which  will  permit  of  such  type  to  be 
seen  and  a  near  point  to  be  measured.  But  in  this  case  we  will 
content  ourselves  with  the  near  point  for  the  larger  type,  as  this 
will  doubtless  show  a  lens  as  strong  as  it  would  be  wise  to  give  to  a 
person  who  has  not  heretofore  worn  glasses. 

We  have,  then,  a  near  point  of  twelve  inches — will  some  gen- 
tleman tell  me  what  lens  represents  this  distance  ? 

"  Three  and  a  quarter  diopters." 

Yes,  that  is  right ;  a  lens  of  thirteen  inches  focal  distance, 
which  is  equivalent  to  3. 25  D. 

Will  some  other  gentleman  tell  us  what  lens  represents  the 
desired  near  point? 

' '  Five  diopters. ' ' 

Correct  ;  we  must  have  a  near  point  of  eight  inches,  which  is 
equivalent  to  5  D. 

Now,  then,   I  will  write  the  problem  and  the  result  on  the 

blackboard  :  _. 

5.00  D. 

3-  25  P. 
+  1-75  D. 

The  glass  representing  the  receded  near  point  (3.25  D. )  is  sub- 
tracted from  the  glass  representing  the  desired  near  point  (5  D. ). 

Theoretically,  then,  +  1.75  D.  lenses  would  be  right  to  afford 
good  vision  of  the  medium-size  type  at  the  proper  reading  distance. 
We  place  this  number  in  the  trial  frame  and  hand  it  to  the  patient. 
He  tells  us  these  lenses  make  reading  very  clear  and  distinct,  and 
that  he  can  even  read  the  very  small  print  at  the  top  of  card. 

In  answer  to  our  question,  he  tells  us  he  wants  rimless  specta- 
cles, and  I  will  now  proceed  to  take  the  necessary  measurements 
for  the  same,  using  this  opportunity  to  give  you  a  few  hints  on  the 
subject  of 

MEASUREMENTS    FOR    SPECTACLES 

Your  work  is  not  finished  when  you  have  completed  the  exam- 
ination of  the  eyes  of  your  patient  and  determined  the  amount  and 


Adjustment  of  Spectacles  2 1 7 

character  of  the  error  of  refraction  present.  The  correcting  lenses 
must  be  set  in  suitable  frames  or  mountings,  which  will  not  only  be 
durable,  but  of  attractive  appearance  and  neatly  fitted  to  the  face, 
so  that  the  glasses  may  prove  satisfactory  in  every  way  not  only  to 
the  wearer  himself,  but  to  his  family  and  friends. 

If  you  do  not  possess  a  good  practical  knowledge  of  the  proper 
placing  of  glasses  before  the  eyes,  the  benefits  that  are  naturally  to 
be  expected  from  a  careful  measurement  and  an  accurate  correction 
of  errors  of  refraction  will  be  wanting. 

Of  late  years  many  advances  and  improvements  have  been 
made  in  the  manufacturing  of  comfortable  and  handsome  contriv- 
ances for  holding  glasses  before  the  eyes,  and  these  are  all  the  more 
necessary  in  order  to  meet  the  increasing  use  of  prismatic  and 
cylindrical  lenses. 

Some  of  your  patients  will  have  decided  views  of  their  own  as 
to  what  they  want  in  the  way  of  a  frame  or  mounting  ;  sometimes 
they  are  right,  sometimes  wrong.  In  the  latter  case  you  should 
have  such  a  knowledge  of  frames  and  mountings  as  to  be  able  to 
clearly  explain  to  your  patient  the  falsity  of  his  ideas.  Many  other 
patients  will  come  to  you  with  no  fixed  ideas,  and  then  you  are  free 
to  select  for  them  down  to  every  detail  just  what  seems  to  be  best 
suited  to  their  peculiarities. 

Sometimes  when  you  have  spent  a  good  deal  of  time  in  working 
out  an  intricate  case  of  refractive  error,  and  when  perhaps  there  are 
several  patients  waiting  for  you,  there  may  be  a  temptation  to  slight 
this  important  branch  of  your  art.  You  may  feel  that  you  have 
done  good  work  in  estimating  the  refraction,  and  that  everything 
else  will  take  care  of  itself.  You  may  take  it  for  granted  that  the 
patient  must  see  properly  with  the  lenses  which  you  have  spent  so 
much  time  in  formulating  when  once  they  are  placed  before  his 
eyes,  forgetting  perhaps  for  the  time  that  no  matter  how  accurate  a 
correction  the  lenses  represent,  they  lose  part  of  their  effect  or  have 
an  improper  effect,  if  they  do  not  occupy  the  proper  position  before 
the  eyes.  Hence  such  lenses  may  not  only  fail  to  do  good,  but 
may  even  do  actual  harm.  Such  being  the  case,  the  importance  of 
the  proper  adjustment  of  the  lenses  becomes  a  matter  of  great 
importance. 

In  these  days  when  the  optometrist  is  striving  to  place  himself 
on  a  plane  above  the  ordinary  seller  of  spectacles,  you  should 
perfect  yourself  as  well  in  the  mechanical  branch  of  the  work  as  in 


218  Clinics  in  Optometry 

the  scientific.  One  supplements  the  other  and  either  is  incomplete 
without  the  other.  This  calls  for  careful  measurements  of  the  face, 
and  when  the  glasses  are  ready  for  delivery  ample  time  should  be 
given  to  their  satisfactory  adjustment,  and  the  patient  impressed 
with  the  importance  of  keeping  them  so,  and  requested  to  return 
as  often  as  necessary  for  that  purpose. 

TWO    STYLES    OF    SPECTACLES 

As  you  already  know,  there  are  two  general  divisions  of  the 
mechanical  construction  that  holds  the  lenses  in  place,  viz. ,  frames 
and  mountings.  The  word  frames  applies  to  that  form  in  which 
the  edges  of  the  lens  are  beveled  so  as  to  enter  a  grooved  wire 
which  surrounds  it  and  holds  it  in  position.  This  is  the  strongest 
form  of  spectacle,  and  should  always  be  prescribed  for  children  and 
workmen  whose  occupation  renders  glasses  liable  to  breakage. 

The  word  mountings  is  used  for  the  supporting  parts  of  "  rim- 
less "  or  "  frameless  "  or  "  skeleton  ' '  glasses.  These  are  preferred, 
especially  by  the  ladies,  for  their  beauty  and  inconspicuousness. 
The  edges  of  the  lenses  should  be  finished  dull,  as  otherwise  if 
polished  they  reflect  the  light  unpleasantly.  The  one  great  disad- 
vantage of  frameless  spectacles  is  their  liability  to  breakage,  on 
account  of  the  weakening  of  the  glass  at  the  points  where  they  are 
drilled  for  the  mountings,  and  they  lack  the  support  and  strength 
which  is  afforded  by  a  rim  around  the  lenses. 

PUPILLARY    DISTAN'CE 

The  normal  position  for  which  glasses  should  be  fitted  is  when 
the  eyes  are  directed  straight  forwards,  the  visual  axes  correspond 
in  position  with  the  center  of  the  lenses,  the  optical  and  geometrical 
centers  coinciding.  Glasses  are  sometimes  purposely  decentered 
to  gain  their  prismatic  effect,  but  ordinarily  we  fit  them  so  that  the 
center  of  the  pupil  lies  directly  behind  the  optical  center  of  the  lens. 

If  the  object  looked  at  was  always  in  the  same  position  and  at 
the  same  distance,  this  would  be  a  simple  matter  ;  but  as  the  pupils 
are  4  to  6  mm.  closer  when  looking  at  a  near  object  than  in  distant 
vision,  we  must  compromise  somewhat  between  that  position  of 
the  eyes  in  which  the  glasses  will  be  most  used  and  the  position  in 
which  they  will  be  less  used. 

When  glasses  are  to  be  used  for  near  work  only,  they  may  be 
decentered  in  2  or  3  mm.  on  each  side  from  the  normal  position  for 


Adjustment  of  Spectacles 


219 


distance,  or,  what  amounts  to  the  same  thing,  the  pupillary  distance 
of  reading  spectacles  should  be  less  than  if  intended  for  distant 
vision  ;  4  mm.  for  a  working  distance  of  fifteen  inches,  6  mm. 
narrower  for  a  distance  of  ten  inches. 

Fortunately,  it  is  only  in  strong  lenses  that  any  considerable 
amount  of  prismatic  effect  is  developed  by  slight  decentering,  and 
here  the  greatest  care  must  be  observed.  But  in  the  large  number 
of  cases  where  low-power  lenses  are  worn,  any  possible  prismatic 
effect  is  not  marked. 

The  most  important  measurement,  then,  is  the  pupillary  dis- 
tance ;  that  is,  the  distance  from  the  center  of  the  pupil  of  one  eye 
to  the  center  of  the  other.      This  can  be  measured  by  a  ruler  held 


before  the  eyes,  the  patient  being  requested  to  look  at  some  distant 
object,  while  you  take  your  position  in  front  and  to  the  side  of 
patient.  The  edge  of  the  rule  should  be  marked  in  millimeters  or 
sixteenths  of  an  inch,  and  the  zero  mark  placed  at  the  inner  border 
of  one  iris,  while  the  thumb  is  moved  along  the  edge  until  it  comes 
to  the  outer  border  of  the  other  iris,  where  the  pupillary  distance 
can  be  read  off.  This  gives  the  pupillary  distance  more  accurately 
than  trying  to  measure  from  the  center  of  one  pupil  to  the  center 
of  the  other,  because  the  line  between  the  iris  and  the  sclerotic 
affords  a  better  basis  for  measurement.  The  average  distance  is 
about  60  mm.  or  2^  inches. 

Inasmuch  as  you  are  necessarily  somewhat  close  to  the  patient 
in  taking  this  measurement,  the  apparent  distance  will  be  a  little 
less  than  the  actual  distance.  Therefore,  it  is  well  to  add  about  2 
mm.  to  the  reading  of  the  rule,  in  order  to  obtain  the  true  inter- 
pupillary  distance. 


220  Clinics  in  Optometry 

Or  have  the  room  darkened  and  the  patient  look  at  a  small 
light  across  the  room,  when  a  small  brilliant  light  will  be  seen  in  the 
center  of  each  cornea.  These  corneal  reflections  mark  the  visual  axes 
of  the  eyes,  and  the  distance  between  them  can  be  easily  measured. 

In  addition  to  these  methods,  I  am  accustomed  to  use  a  trial  frame 
and  a  piano  lens  before  each  eye,  marked  with  cross  lines,  as  shown 
in  the  illustration  on  the  preceding  page. 

The  thumb-screw  is  then  rotated,  thus  approximating  or  sep- 
arating the  lenses,  until  the  point  of  crossing  of  the  lines  is  directly 
in  front  of  the  center  of  each  pupil.  The  frame  is  then  removed  and 
the  pupillary  distance  is  read  off  the  scale  or  measured  by  the  rule. 

BRIDGE    DIMENSIONS 

The  next  point  to  be  considered  is  the  height  of  bridge,  which 
is  the  distance  from  a  line  passing  through  the  centers  of  the  lenses 
to  the  lower  edge  of  the  bridge. 

If  a  rule  be  held  horizontally  before  the  patient's  eyes  with  its 
edge  resting  on  the  bridge  of  the  nose  and  at  the  natural  position 
for  the  spectacle  bridge,  the  height  of  this  edge  of  the  rule  above 
the  pupils  will  show  at  a  glance  about  how  high  the  top  of  the 
bridge  should  be. 

I  will  now  proceed  to  take  these  measurements  on  the  patient 
before  us,  so  that  you  may  see  exactly  how  it  is  done.  I  will  ask 
the  gentleman  to  look  out  of  the  window  at  extreme  distance.  I 
stand  to  one  side  so  as  not  to  obstruct  his  view,  and  place  the  zero 
of  the  rule  at  inner  edge  of  the  iris  of  right  eye,  and  run  my 
thumb-nail  along  the  edge  until  it  reaches  the  outer  edge  of  the 
iris  of  the  other  eye,  where  I  read  63  mm. ,  which  is  about  two  and 
one-half  inches.  This  is  the  pupillary  distance  for  distant  vision, 
but  as  this  gentleman  desires  to  use  his  glasses  for  reading  only,  we 
will  deduct  4  mm.,  making  the  p.  d.,  which  we  will  write  in  the 
prescription,  59  mm. 

I  will  now  place  the  rule  once  again  on  the  bridge  of  the  nose 
and  compare  its  edge  with  an  imaginary  line  joining  the  centers  of 
the  two  pupils.  In  this  case,  as  you  see,  the  edge  of  the  rule  is 
above  this  line,  and,  taking  another  rule,  we  will  measure  it  (verti- 
cally, of  course)  and  find  it  to  be  about  a  quarter  of  an  inch, 
or  6  mm. 

The  inclination  of  the  bridge  is  the  next  point  to  be  deter- 
mined.     Once  again  we  bring  our  rule  into  use,  placing  it  in  the 


Adjustment  of  Spectacles  2  2 1 

same  position  as  heretofore.  The  patient  is  requested  to  wink,  and 
we  notice  what  relation  the  tips  of  the  lashes  bear  to  the  edge  of 
the  rule.  If  they  sweep  over  this  edge,  then  the  bridge  must  be 
back  of  the  plane  of  the  glasses,  or,  in  other  words,  the  inclination 
of  the  bridge  must  be  "in,"  so  as  throw  the  lenses  out.  If  the 
lashes  barely  escape  the  edge  of  the  rule,  then  the  bridge  at  its  top 
and  the  lenses  must  be  on  the  same  plane,  and  the  inclination  of  the 
bridge  is  "  o. "  If  the  tips  of  the  lashes  are  back  of  the  edge  of 
he  rule,  then  we  note  how  much  closer  they  may  be  brought  to  the 
edge  of  the  rule  without  touching.  This  indicates  that  the  top  of  the 
bridge  of  the  spectacles  must  be  in  front  of  the  plane  of  the  lenses, 
or,  in  other  words,  that  the  inclination  of  the  bridge  must  be  "  out." 

We  take  this  measurement  in  the  case  before  us  and  find  that 
the  tips  of  the  lashes  are  about  2  mm.  back  of  the  edge  of  the  rule, 
and  we  will,  therefore,  order  the  inclination  of  the  bridge  2  mm.  out. 
You  will  understand  when  the  nose  is  prominent,  the  inclination  of 
bridge  must  be  out  ;  while  in  the  case  of  a  flat  nose,  the  inclination 
of  the  bridge  must  be  in. 

The  width,  of  the  base  of  the  bridge  is  the  next  measurement. 
This  is  the  width  of  the  nose  where  the  bridge  at  its  widest  opening 
will  touch  it,  and  is  usually  back  of  the  plane  of  the  lenses.  This 
can  be  obtained  by  a  pair  of  blunt  compasses,  the  points  of  which 
are  placed  where  the  shanks  of  the  bridge  would  rest.  In  this  case 
we  find  it  to  be  18  mm. 

We  Have  now  taken  the  four  principal  measurements  for  spec- 
tacle fitting,  viz  : 

Pupillary  distance, 

Height  of  bridge, 

Inclination  of  bridge, 

Width  at  base. 

As  a  matter  of  fact,  the  best  way  to  obtain  or  to  verify  these 
dimensions  is  by  means  of  a  set  of  ' '  fitting  frames, ' '  which  are 
made  to  correspond  with  standard  sizes  of  bridges,  and  numbered 
and  lettered  accordingly.  It  has  been  recommended  that  this  letter 
and  number  then  be  given  in  order  to  save  time  in  taking  measure- 
ments and  writing  prescriptions,  but  I  would  advise  you  to  compare 
the  four  measurements  you  desire  with  those  afforded  by  the  fitting 
frame  you  have  selected,  and  write  each  one  of  the  measurements 
separately,  thus  affording  you  an  opportunity  to  make  any  altera- 
tion in  either  one  of  them  that  may  be  necessary. 


222  Clinics  in  Optometry 

We  try  the  fitting  frame  marked  N  2,  and  placing  it  on 
patient's  face,  it  seems  to  be  a  fairly  good  fit.  Now  let  us  examine 
each  measurement  in  detail. 

The  p.  d.  of  this  frame  is  60  mm.,  but  for  reasons  already 
mentioned  we  wish  to  order  59  mm.  The  height  of  this  bridge 
is  %  inch,  but  this  does  not  allow  the  lenses  to  sit  quite  low  enough 
for  reading,  and  I  think  we  had  better  increase  this  distance  and 
order  8  mm.  for  height  of  bridge.  The  inclination  of  this  bridge 
is  Ty  out  ;  this  holds  the  lenses  a  very  slight  distance  from  the  tips 
of  the  lashes,  so  we  will  order  2  mm.  out  as  we  originally  found  it. 
The  base  of  this  bridge  is  -ff,  which  is  equal  to  about  19  mm. 
This  appears  to  be  a  very  comfortable  fit,  and  so  will  order  19  mm. 
instead  of  18  mm.  as  per  our  original  measurement. 

It  has  taken  me  some  time  to  describe  these  procedures  and 
make  these  measurements,  but  with  a  set  of  fitting  frames  and  a 
rule  and  a  little  experience,  they  can  be  taken  satisfactorily  in  a 
minute  or  two. 


Fitting  of  Eyeglasses 


[Clinic  No.  34] 

Miss  Kate  C,  aged  31  years.  She  tells  us  that  she  has  been 
employed  at  a  dressmaker's,  but  that  her  eyes  troubled  her  so 
much  she  was  compelled  to  give  up  sewing  and  seek  a  position  at 
domestic  service.      She  has  never  worn  glasses. 

We  find  acuteness   of  vision   in  right  eye  to  be  ££  an(^  left 

eye  U- 

The  ophthalmometer  shows  an  excess  of  curvature  in  the  80th 
meridian  of  2  D.  for  the  right  eye,  and  of  3  D.  in  the  70th  meridian 
for  the  left  eye.  This  indicates  the  probable  presence  of  an  astig- 
matism with  the  rule. 

We  hand  her  the  reading  card  in  order  to  determine  the  posi- 
tion of  the  near  point  and  the  amount  of  amplitude  of  accommoda- 
tion. She  is  unable  to  read  the  smallest  type,  but  she  can  see  the 
second  size,  marked  .75  D.,  with  which  her  near  point  is  eight 
inches,  equivalent  to  an  amplitude  of  accommodation  of  5  D. 

Perhaps  the  thought  may  strike  some  of  you  that  this  is  all 
right,  as  you  recall  the  standard  of  near  point  and  accommo- 
dation which  has  been  fixed  for  presbyopia.  But  I  hasten  to 
say  that  such  reasoning  does  not  apply  in  this  case  because  this 
patient  is  but  little  over  30  years  of  age,  and  therefore  cannot 
be  presbyopic. 

What  inference  can  be  drawn  and  information  gained  from  this 
near  point  of  eight  inches  ?  It  shows  a  refractive  power  less  than 
normal  and  raises  at  once  the  presumption  of  hypermetropia. 

Will  some  gentleman  tell  us  what  is  the  normal  near  point  and 
amplitude  of  accommodation  at  this  age  ? 

"Five  and  one-half  inches,  equaling  7  D.  of  amplitude  of 
accommodation. 

Yes,  that  is  correct  :  we  should  have  7  D.  of  accommodation, 
but  we  have  only  5  D.  There  is  therefore  a  deficiency  of  2  D.  in 
the  accommodative  power,  most  probably  due  to  a  hypermetropic 
condition  of  refraction.  Therefore  it  is  fair  to  assume  that  the 
astigmatism  revealed  by  the  ophthalmometer  is  of  the  hypermetro- 
pic variety,  or  that  there  is  some  hypermetropia  combined  with  it. 


2  2\  Clinics  in  Optometry 

We  will  now  proceed  with  our  test  case  examination,  com- 
mencing with  the  right  eye  as  usual.  Following  our  routine 
we  try  a  +  .50  D.  sphere.  This  is  neither  accepted  nor  rejected, 
it  does  not  make  the  letters  any  better  or  any  worse.  We 
now  try  a  -f-  .  50  D.  cylinder,  placing  the  axis  at  8o°  as  indicated 
by  the  ophthalmometer.  This  is  at  once  accepted  as  improving 
vision,  thus  verifying  the  presence  of  astigmatism  at  least  to  this 
amount. 

With  this  cylinder  in  place  we  hold  in  front  of  it  first  a  +  .  50 
D.  sphere  and  then  a  -f  .50  D.  cylinder  with  axis  in  same  position, 
at  the  same  time  asking  the  patient  which  she  prefers.  She  unhesi- 
tatingly chooses  the  latter,  thus  making  the  cylindrical  value  in  front 
of  her  eye  equal  to  a  +  1  D.  We  remove  the  +  •  5°  D-  cylinder 
and  replace  it  with  a  +  1  D.  cyl.  axis  8o°  which  improves  vision 
\  almost. 

We  repeat  the  same  procedure,  viz. ,  placing  a  +  .  50  D.  sphere 
and  then  a  +  .50  D.  cylinder  in  front  of  the  +  1  D.  cylinder 
in  the  trial  frame,  and  ask  the  patient  which  affords  the  greatest 
improvement  in  vision.  She  prefers  the  cylinder,  which  makes  the 
cylindrical  value  +  1.50  D.  We  place  a  +  1.50  D.  cylinder  in 
the  trial  frame,  which  affords  a  vision  of  \%.  We  once  again  repeat 
our  former  procedure  of  trying  a  +  .  50  D.  sphere  and  a  +  .  50  D. 
cylinder,  but  this  time  both  are  rejected.  We  try  a  +  .25  D. 
sphere  and  a  +  .25  D.  cylinder,  but  they  also  are  rejected.  We 
are  therefore  justified  in  assuming  that  this  is  a  case  of  simple 
hypermetropic  astigmatism  with  the  rule  amounting  to  1.50  D. 
We  rotate  the  cylinder  io°  or  150  to  the  left,  and  then  io°  or  150 
to  the  right,  in  each  case  producing  a  marked  impairment  of  vision, 
thus  proving  that  8o°  is  the  proper  position  for  the  axis  of  the 
cylinder,  and  verifying  the  reading  of  the  ophthalmometer. 

We  now  take  up  the  examination  of  the  left  eye,  going  through 
exactly  the  same  procedures,  and  the  result  we  find  to  be  +  2  D. 
cylinder  axis  700,  with  which  vision  equals  \%.  This  is  the  best  we 
can  do  for  the  left  eye.  You  will  frequently  meet  with  cases  where 
it  is  impossible  to  raise  the  vision  in  both  eyes  to  normal,  and  very 
many  times  it  is  the  left  eye  that  falls  below  the  standard. 

In  order  to  make  our  examination  complete,  we  will  make  use 
of  the  ophthalmoscope,  retinoscope  and  muscle  tests,  but  we  will 
pass  these  over  for  the  present,  in  order  to  devote  some  attention 
to  eyeglass  fitting. 


Fitting  of  Eyeglasses  225 

THE    FITTING   OF    EYEGLASSES 

This  lady,  like  most  of  her  class,  objects  to  wearing  spectacles. 
We  tell  her  that  they  will  afford  her  more  satisfaction  and  that  her 
nose  is  scarcely  suited  for  eyeglasses,  in  spite  of  which  she  insists  on 
the  latter  ;  and  as  it  always  pays  to  please  the  ladies,  we  will  make 
an  effort  in  that  direction. 

The  measurements  for  eyeglasses  are  in  some  particulars  the 
same  as  for  spectacles,  and  yet  there  is  quite  a  difference.  There 
are  no  temples  or  bridge,  but  in  place  of  these  we  have  the  guards 
and  spring,  which  are  made  in  many  varieties  and  sizes  ;  in  fact 
the  market  is  flooded  with  various  guards,  springs,  and  devices  for 
holding  the  glasses  in  place,  and  it  would  be  as  impossible  for  me 
to  mention  and  describe  them,  as  it  would  be  for  you  to  keep  on 
hand  samples  of  all  of  them. 

The  pupillary  distance  will  be  measured  in  exactly  the  same 
way  as  for  spectacles,  but  in  the  case  of  eyeglasses  it  must  be  got- 
ten by  bending  the  shank  of  the  guards,  or  by  increasing  the 
length  of  the  posts  or  the  size  of  the  eyeglasses. 

SIZES   OF    EYES    OR    LENSES 

The  various  shapes  and  sizes  are  designated  as  follows  :  4,  3, 
2,  1,  0  and  00,  number  4  being  the  smallest  and  00  the  largest. 
Specially  large  sizes  are  000,  0000  and  jumbo.  The  No.  4  is  34 
mm.  wide,  and  there  is  a  gradual  increase  of  1  mm.  until  we  reach 
the  00  eye  which  is  40  mm.  wide.  The  jumbo  or  largest  size  is  47 
mm.  wide. 

The  size  of  the  lenses  should  be  in  keeping  with  the  size  of  the 
face  and  the  inter-pupillary  distance.  00  eye  is  the  usual  size  for  a 
male  adult,  o  eye  for  a  female  adult,  and  2  eye  for  a  child.  An  00 
eye  is  usually  suitable  for  a  pupillary  distance  of  2^  inches,  an  o 
eye  for  a  p.  d.  of  2%  inches,  1  eye  for  a  p.  d.  of  two 
inches,  and  a  2  eye  for  a  p.  d.  of  less  than  two  inches.  The  tend- 
ency in  these  days  is  to  order  lenses  of  larger  sizes  than  formerly, 
which  I  think  is  to  the  advantage  of  the  patient's  sight. 

By  a  little  measurement  we  are  able  to  determine  whether  any 
certain  size  lens  is  suitable  for  any  particular  patient.  To  do  this 
we  must  subtract  the  width  of  the  bridge  (or  in  eyeglasses  the  dis- 
tance between  the  inner  edges  of  the  two  lenses)  from  the  pupillary 
distance,  and  the  result  will  be  the  space  at  our  disposal  for  the 


226  Clinics  in  Optometry 

inner  halves  of  the  two  lenses,  which  is  just  equivalent  to  the  total 
width  of  one  lens.  If  the  amount  of  space  is  not  sufficient,  the  size 
of  the  eye  must  be  lessened,  while  if  there  is  space  to  spare  the  eyes 
can  be  made  larger  if  it  is  thought  desirable. 

For  instance,  suppose  you  had  chosen  an  oo  eye  as  suitable 
for  the  face,  and  you  found  the  width  of  the  bridge  to  be  20  mm. , 
and  the  p.  d.  60  mm.  This  leaves  40  mm.  for  the  inner  halyes  of 
the  two  lenses,  which  is  just  right  because  the  size  of  an  00  eye  is 
40  mm.  in  frameless.  Whereas,  if  the  bridge  took  up  more  than  20 
mm.  of  the  60  mm.  p.  d.,  then  the  increase  in  the  width  of   the 

/*\  ^x  J^  A 

A  B  CD  K 

Different  Sizes  of  Studs 

bridge  must  be  deducted  from  the  size  of  the  lenses.  In  other 
words,  the  size  of  the  lenses  must  be  made  to  correspond  to  the 
available  space  :  we  can  lessen  the  size  of  the  lenses,  but  we  cannot 
lessen  the  width  of  the  nose  as  shown  by  the  bridge. 

In  the  case  of  eyeglasses  we  can  increase  the  p.  d.  by  increas- 
ing the  size  of  the  lenses,  as  for  instance  a  No.  2  eye  is  36  mm. 
wide  while  an  00  eye  is  40  mm.  wide,  and  therefore  we  gain  4  mm. 
in  p.  d.  by  using  the  latter. 

In  addition  we  can  control  the  p.  d.  in  eyeglasses  by  the  dif- 
ferent lengths  of  studs.  There  are  five  standard  lengths,  marked 
A,  B,  C,  D  and  E,  the  A  being  the  shortest  and  the  E  the  longest. 
The  A  stud  is  about  3  mm.  long  and  the  E  stud  about  9  mm.  long, 
so  that  by  using  the  latter  we  can  gain  6  mm.  on  each  side  ;  in 
other  words,  we  can  increase  the  p.  d.  12  mm.  by  using  the  E  studs, 
or  any  intermediate  gain  in  p.  d.  by  using  one  of  the  other  lengths 
of  studs. 

THE   SPRING 

The  spring  comes  in  different  shapes  and  sizes  :  oval  or  round, 
semi-oval  and  flat,  and  varying  in  length  from  1^  inches  to  2^ 
inches.  The  width  of  the  nose  where  the  guards  are  to  fit  should 
be  taken,  in  order  to  get  some  indication  as  to  the  size  of  spring  : 
if  the  nose  is  narrow  a  shorter  spring  will  suffice  than  if  the  nose  is 
large  and  broad  at  its  base. 


Fitting  of  Eyeglasses 


227 


The  choice  between  a  round  or  fiat  spring  is  largely  a  matter 
of  taste,  although  in  my  opinion  a  round  spring  looks  best  on  a 
full  face  and  a  flat  spring  best  on  a  small  or  narrow  face. 

The  nearness  of  the  lenses  to  the  eyes  can  be  regulated  by  the 
guards,  by  the  spring  and  by  the  studs. 

The  guards.  If  the  bearing  surface  of  the  guards  is  made 
to  slant  obliquely  outwards  from  front  to  back,  the  lenses  will  be 
allowed  to  approach  closer  to  the  eyes.  If  the  guards  are  bent  so 
that  the  bearing  surface  is  straighter,  the  lenses  will  be  thrown  a 
little  farther  from  the  eyes. 

The  position  of  the  lenses  can  also  be  regulated  by  the  length 
of  the  arm  of  the  guards.  If  the  arm  is  long  the  lenses  are  held 
farther  away  :  if  the  arm  is  short,  the  lenses  are  brought  closer  to 
the  eyes.  The  same  thing  can  be  accomplished  by  so-called  wide- 
angle  and  close-angle  guards. 

Out  of  the  many  kinds  of  guards  on  the  market,  we  should 
select  the  simplest  and  the  one  that  will  permit  of  whatever  bend- 
ing is  necessary  to  adapt  the  bearing  surfaces  to  the  slope  of  the 
nose.  The  guard  that  meets  the  requirements  in  the  greatest  num- 
ber of  cases  is  the  No.  1  shell  guard.  In  the  hands  of  an  optome- 
trist who  is  experienced  in  its  adjustment,  this  guard  can  be 
satisfactorily  fitted  to  nine-tenths  of  the  noses  you  meet.  Then 
there  is  No.  3,  which  is  a  close-angle,  short-arm  guard,  and  brings 


Different  Styles  of  Guards 


the  lenses  closer  to  the  eyes.  Also  No.  5,  which  is  a  wide-angle, 
long-armed  guard,  and  throws  the  lenses  farther  away.  As  soon  as 
you  try  a  pair  of  No.  1  guards  on  your  patient,  you  can  see  at  a 
glance  whether  lenses  are  at  right  distance  from  eyes  or  whether 
they  should  be  closer  or  farther,  in  which  case  the  indications  for 
Nos.  3  and  5  will  present  themselves  to  you.  Nos.  6  and  7  are 
used  when  the  lenses  set  too  high,  and  when  it  is  desired  to  throw 
them  down  as  for  reading. 


228  Clinics  in  Optometry 

The  guards  are  lined  with  shell  or  cork  and  such  have  hereto- 
fore been  almost  exclusively  used.  But  the  tendency  at  the  present 
day  is  to  prefer  the  all-metal  guards  as  more  cleanly  and  more  sani- 
tary. These  unlined  guards  can  be  more  easily  adjusted  and  bent, 
as  there  is  no  danger  of  breaking  the  shell  or  defacing  the  cork. 

The  Spring.  The  "  Grecian  "  spring,  which  curves  outwards, 
allows  the  lenses  to  come  closer  to  the  eyes  than  the  straight  spring. 
The  weight  of  the  spring  depends  somewhat  upon  the  strength  of 
the  lenses  :  if  the  power  is  low  and  the  lenses  light,  a  reduced  or 
light  weight  spring  will  answer  ;  whereas,  if  the  lenses  are  strong 
and  thick  and  heavy,  a  more  substantial  spring  may  be  needed. 

The  Studs.  When  the  Grecian  spring  will  not  allow  the 
lenses  to  come  close  enough  to  the  eyes,  then  we  can  make  use  of 
so-called  "inset  studs,"  which  can  be  procured  of  several  lengths 
to  bring  lenses  Ty  or  }&"  closer  as  may  be  desired.  Or  if  the  eyes 
are  projecting  and  it  becomes  necessary  to  hold  the  lenses  farther 
away,  the  same  studs  can  be  used  by  reversing  their  direction, 
making  them  "  outset  studs." 

The  height  of  the  lenses  can  be  regulated  by  the  guards  and 
by  the  position  in  which  the  holes  are  drilled  for  the  mountings. 

The  Guards.  This  depends  upon  the  position  at  which  the 
arm  is  attached  to  the  guard.  The  usual  place  is  in  the  middle  of 
the  guard  where  it  holds  the  lenses  in  proper  position  for  the 
majority  of  persons.  If  this  is  too  low,  the  attachment  of  the  arm 
to  the  upper  part  of  the  guard  will  raise  the  lenses  :  if  too  high,  the 
attachment  of  the  arm  to  the  lower  part  of  guard  (as  in  Nos.  6  and 
7)  will  lower  them. 

Position  of  holes.  Ordinarily  the  hole  is  drilled  on  a  plane 
with  the  center  of  the  lenses,  which  answers  for  the  majority  of 
persons.  If  this  allows  patient  to  see  under  the  lenses,  or  if  the 
glasses  are  desired  for  reading  only,  the  lenses  may  be  ordered 
"drilled  above  center,"  fa"  or  }i"  as  may  be  necessary,  thus 
lowering  the  glasses  this  much. 

But  the  most  practical  way  to  take  the  measurements  for  eye- 
glass mountings  is  to  try  them  on  the  nose,  and  for  this  purpose  it 
is  necessary  to  have  a  comprehensive  set  of  samples.  These  should 
be  fitted  with  piano  lenses  and  neatly  made,  so  as  to  make  a  good 
impression  on  the  patient  on  whom  they  are  tried.  The  eyes 
should  be  of  various  shapes  and  sizes,  and  it  is  a  good  idea  to  have 
them  marked  with  a  vertical  and  a  horizontal  line  crossing  each 


Fitting  of  Eyeglasses  229 

other  at  the  center  of  the  lens.  These  sample  fitting  eyeglasses 
should  show  the  different  lengths  of  studs,  offset  and  inset  studs, 
and  also  the  various  styles  of  springs  and  the  guards  that  are  most 
commonly  used. 

With  such  a  set  of  sample  fitting  eyeglasses,  embracing  the 
most  important  styles  of  guards,  studs,  springs,  and  the  several 
sizes  of  eyes,  it  is  a  comparatively  easy  matter  to  select  the  one 
that  comes  nearest  to  holding  the  lenses  in  the  proper  position  and 
to  maintain  a  secure  hold  on  the  nose  and  at  the  same  time  feel 
easy  and  comfortable. 

In  order  that  the  eyeglasses  may  keep  their  proper  position 
without  slipping,  it  is  important  that  the  guards  bear  uniformly  on 
the  nose  along  their  whole  surface,  with  just  a  little  slope  to  make 
the  anterior  edge  of  the  guards  fit  slightly  closer.  Also  that  the 
tops  of  the  guards  may  be  approximated  a  trifle  so  as  to  bring  the 
pressure  above  the  bridge  of  the  nose  in  the  fleshy  portion  and  not 
on  the  bone,  which  makes  it  more  comfortable  and  more  apt  to 
stay  on.  At  the  same  time  care  should  be  taken  to  see  that  the 
lenses  are  properly  centered  both  vertically  and  horizontally. 

It  is  really  a  fact  that  scarcely  any  pair  of  spectacles,  much  less- 
eyeglasses,  will  fit  perfectly  without  a  certain  amount  of  adjustment. 
No  matter  how  carefully  you  take  your  measurements,  how  cor- 
rectly you  write  the  dimensions  on  the  prescription  or  how  accur- 
ately the  manufacturer  fills  your  order,  yet  when  you  get  the 
glasses  and  try  them  on  the  patient's  face,  they  may  fail  to  be  a 
perfect  fit. 

Has  there  been  any  error  on  your  part  or  the  manufacturers  ? 
Probably  not.  The  final  adjustment  must  be  made  on  the  face  that 
is  to  wear  the  glasses.  For  instance,  if  a  pair  of  eyeglasses  were 
ordered  with  the  guards  14  mm.  apart  at  the  top  and  20  mm.  apart 
at  the  bottom,  and  the  slant  of  the  nose  was  a  little  different  on  one 
side  from  the  other,  the  glasses  would  be  tilted  up  on  the  side  that 
was  the  fullest,  and  the  set  of  the  glasses  would  be  wrong  even 
though  the  nose  dimensions  as  given  were  correct. 

Or  in  the  case  of  spectacles  :  if  one  ear  was  a  little  higher  than 
the  other  or  one  side  of  the  head  a  little  fuller  than  the  other,  the 
glasses  will  not  be  straight,  or  one  lens  will  stand  farther  from  the 
face  than  the  other. 

One  other  practical  point  :  the  glasses  may  be  adjusted  cor- 
rectly at  the  first  sitting,  and  yet  get  out  of  adjustment  later  on  as 


230  Clinics  in  Optometry 

they  settle  to  their  permanent  resting  place  on  the  face.  Therefore, 
it  is  always  well  to  suggest  to  the  patient  that  he  return  in  a  few 
weeks  for  a  refitting  or  sooner  if  necessary,  as  otherwise  he  may 
condemn  you  for  not  having  made  a  good  job  of  the  fitting. 

There  are  two  ways  of  adjusting  glasses,  with  the  fingers  and 
with  the  pliers.  It  is  wonderful  what  some  persons  can  do  to 
frames  and  mountings  with  their  fingers,  but  for  good  work  we 
prefer  the  pliers.  There  is  always  danger  in  using  them,  especially 
for  frameless  work,  even  if  you  are  skilled.  The  best  way  is  to  have 
the  measurements  in  your  prescription  so  accurate  that  your  need 
for  pliers  will  be  reduced  to  a  minimum.  This  applies  when  you 
send  your  orders  to  the  manufacturer,  but  if  you  wish  to  fill  from 
your  own  stock  you  may  have  to  depend  a  great  deal  on  the  pliers. 

It  is  unsatisfactory  to  work  on  steel  with  pliers  as  it  is  likely  to 
snap.  In  gold  filled  goods  the  use  of  pliers  is  apt  to  crack  or 
break  the  thin  outer  coating  of  gold.  Gold  is  the  best  material  to 
work  on  with  pliers,  as  the  metal,  while  tough,  is  also  pliable,  and 
gives  way  under  the  pressure  of  the  tools. 

In  the  use  of  pliers  the  motion  should  be  slow  and  gentle,  with 
the  avoidance  of  any  sudden  twists,  and  producing  the  effect  desired 
by  several  applications  of  the  pliers. 

We  now  turn  to  our  patient  and  carry  out  the  principles  I 
have  just  given  you.  We  find  the  pupillary  distance  to  be  2^6 
inches,  and  I  will  look  among  our  fitting  eyeglasses,  selecting  this 
one,  which  looks  as  if  it  might  fit.  It  has  a  pupillary  distance  of 
2^6  inches,  with  No.  1  shell  guards  and  No.  11  spring.  I  place  it 
on  the  patient's  nose,  and  you  see  the  left  glass  tilts  upwards.  I 
take  my  pliers  and  bend  out  the  bottom  of  the  guard  thus  lowering 
the  lens,  which  now  appears  straight.  I  will  also  bend  the  arms  of 
the  guards  a  trifle  so  as  to  correspond  to  the  slope  of  the  nose,  and 
replacing  the  glasses  you  see  they  are  a  perfect  fit. 

Before  parting,  one  more  word  about  the  pliers.  The  man 
back  in  the  shop  who  is  using  these  tools  all  the  time,  can  do  a 
great  deal  more  of  altering  of  frames  and  mountings  without  spoiling 
their  appearance  than  you  can  out  in  your  office,  and  therefore  you 
should  not  use  them  any  more  than  actually  necessary.  Of  course 
you  must  do  some  adjusting,  but  the  measurements  given  in  the 
prescription  should  be  so  nearly  accurate  that  everything  possible 
in  the  mechanical  line  should  be  done  by  the  man  who  is  accus- 
tomed to  do  this  kind  of  work. 


Spectacles  and  Eyeglasses 


[Clinic  No.  35] 

Mrs.  S.  L.  R.,  aged  60,  complains  of  some  headache,  a  tired 
feeling  in  the  eyes  after  reading,  and  recently  eyes  have  been 
somewhat  inflamed. 

We  find  the  acuteness  of  vision  in  each  eye  to  be  f$. 

The  ophthalmometer  shows  an  excess  in  the  vertical  meridian 
of  i  D. 

With  the  retinoscope  a  +  2  D.  neutralizes  the  motion 
in  the  vertical  meridian,  and  a  +  2.50  D.  in  the  horizontal 
meridian. 

The  ophthalmoscopic  examination  is  negative — the  refracting 
media  are  all  clear  but  a  slight  dullness  in  the  appearance  of  the 
fundus. 

The  test  case  examination  develops  the  following  combina- 
tion, +  1.50  D.  S.  O  +  .50  D.  cyl.  axis  900,  with  which  vision 
equals  f£. 

For  reading  there  is  required  the  addition  of  +  2.50  D.  S., 
making  the  reading  formula,  +  4  D.  S.  O  +  -5°  D.  cyl. 
axis  900. 

This  then  is  a  case  of  compound  hypermetropic  astigmatism 
complicated  with  presbyopia,  calling  for  two  pairs  of  glasses. 

She  decides  she  will  have  spectacles  for  constant  wear,  and 
eyeglasses  for  reading,  thus  giving  us  an  opportunity  to  put  to 
practical  use  the  principles  of  spectacle  and  eyeglass  fitting  which 
I  have  demonstrated  at  the  last  two  clinics,  and  to  throw  out  a  few 
more  hints  along  the  same  lines. 

When  you  meet  a  person  who  would  like  to  have  eyeglasses 
instead  of  spectacles,  but  whose  nose  is  so  flat  and  shallow  that 
eyeglasses  will  not  hold,  it  will  probably  save  you  a'  good  deal  of 
future  trouble  if  you  do  not  attempt  to  fit  them  but  insist  on 
spectacles.  Such  persons  often  have  false  hopes  kindled  in  them 
by  the  advertisements  of  opticians  who,  in  exploiting  the  claims  of 
certain  styles  of  guards,  make  the  extravagant  statement  that  they 
can  be  fitted  to  any  nose. 

231 


232  Clinics  in  Optometry 

When  you  are  fitting  a  person  from  your  sample  stock  of  eye- 
glasses, it  is  not  always  well  to  show  the  various  styles  to  your 
patient  and  leave  the  selection  to  him,  as  he  may  arbitrarily 
select  a  style  which  cannot  be  fitted  to  his  nose.  But  rather 
decide  for  yourself  what  kind  seems  best  adapted  to  his  nose 
and  proceed  to  fit  as  you  think  best.  You  will  be  apt  to  get 
more  satisfactory  results  and  save  time  that  would  have  to  be 
spent  in  argument  and  explanation  as  to  why  certain  styles 
are  not  suitable  for  that  particular  case,  and  besides  the  patient 
may  have  more  confidence  in  your  ability  if  his  opinion  is  not 
asked. 

I  will  now  proceed  to  take  our  measurements,  first  for  the 
spectacles.  This  lady's  face  and  features  are  as  you  see  small  and 
narrow.  I  take  my  rule  and  laying  its  edge  on  the  bridge  of  the 
nose,  according  to  the  directions  I  have  given  you  at  a  previous 
clinic,  I  find  the  p.  d.  to  be  2}i  inches.  The  edge  of  the  rule  is 
about  a  quarter  of  an  inch  above  the  imaginary  line  connecting  the 
centers  of  the  pupils.  The  nose  being  somewhat  sharp  and  slightly 
prominent,  the  edge  of  the  rule  is  a  little  distance  from  the  tips  of 
the  lashes,  so  that  the  inclination  of  the  bridge  will  be  T\/'  out. 
The  width  of  the  base  is  y%" . 

Generally  a  frame  can  be  selected  from  stock  that  will  afford 
the  desired  measurements,  but  not  always.  One  frame  may  have 
the  correct  p.  d.  but  not  the  right  height  of  bridge  :  while  another 
that  has  the  proper  height  of  bridge,  may  be  found  too  wide  or 
too  narrow.  In  such  cases  the  dimensions  which  are  correct  can 
be  taken  from  various  frames,  in  this  way  making  up  the  prescrip- 
tion that  possesses  the  required  data  to  be  sent  to  the  wholesale 
house. 

Occasionally  you  may  meet  with  a  face  on  which  some  of  the 
dimensions  cannot  be  obtained  from  any  of  your  fitting  frames,  or 
there  may  be  a  difference  between  the  two  sides  of  the  face.  Then 
it  becomes  necessary  to  take  the  measurements  as  I  have  already 
shown  you. 

There  is  no  frame  in  our  collection  that  affords  all  the  measure- 
ments desired  in  this  case.  This  frame  which  I  hold  in  my  hand  is 
marked  "M  i}4,"  the  dimensions  of  which  are  as  follows: 
p.  d.  2]^.  ;  height  yV  ;  inclination  -fa  out  ;  base  width  f£.  Two  of 
these  dimensions  are  correct,  the  inclination  of  the  bridge  and  the 
width  of  its  base  ;  but  the  p.  d.  and  height  are  incorrect,  the  one 


Spectacles  and  Eyeglasses  233 

being  too  much  and  the  other  too  little.  So  it  is  with  the  rest  of 
the  frames  ;  where  some  of  the  dimensions  are  right,  the  others  are 
wrong.  However  we  will  try  this  frame  on  the  lady's  face,  and 
note  each  of  the  measurements  desired. 

The  first  glance  shows  that  it  is  too  wide  and  out  of  proportion 
to  the  small  face,  so  that  our  former  measurement  of  2^  inches  is 
verified.  We  notice  that  the  lenses  are  too  high  and  patient  looks 
through  their  lower  edges,  so  that  height  of  bridge  should  be  a 
little  more  than  in  this  frame,  increasing  from  T3F"  to  }(".  The 
lenses  just  escape  the  tips  of  the  lashes,  so  that  we  know  the 
inclination  of  the  bridge  is  right.  The  bridge  fits  the  nose  neatly, 
being  neither  too  tight  nor  too  loose,  so  that  we  assume  our 
measurement  of  width  of  base  is  correct. 

In  regard  to  the  bridge  you  should  always  see  that  when  the 
bridge  rests  at  its  proper  place  that  the  shanks  do  not  press  uncom- 
fortably into  the  inner  canthi.  If  the  shape  of  the  bridge  is  such 
as  to  produce  this  effect,  then  a  bridge  with  short  shanks  should  be 
ordered.  In  other  cases  long  shanks  may  be  required.  The 
inclination  of  the  bridge  is  also  affected  by  the  shanks,  long  shanks 
adding  Ty  and  extra  long  shanks  )&". 

For  instance,  in  this  case  if  this  frame  allowed  the  lashes  to 
brush  slightly  against  the  lenses  :  instead  of  changing  the  inclina- 
tion of  the  bridge  to  throw  the  lenses  farther  from  the  face,  I  could 
order  M  1%  bridge  with  long  shanks,  which  being  Ty  longer, 
would  hold  the  lenses  that  much  farther  from  the  eyes  and  thus 
escape  the  lashes.  Or  if  the  lashes  brushed  the  lenses  a  good 
deal,  I  could  order  M  i}4  with  extra  long  shanks,  which  would 
set  the  lenses  yi"  farther  out  than  the  regular  dimensions  of 
the  bridge. 

In  addition  to  the  four  dimensions  which  I  have  described  to 
you  and  which  I  have  deemed  the  most  important,  there  are  four 
others  which  must  sometimes  be  taken  into  account. 

The  angle  of  the  crest, 

The  angle  of  the  lenses, 

The  width  of  temples, 

The  length  of  temples. 

The  angle  of  the  crest.  This  is  a  measurement  that  is  usually 
neglected,  probably  because  we  take  it  for  granted  that  all  noses 
where  the  bridge  of  the  spectacles  rests,  show  the  same  angle  to 


234  Clinics  in  Optometry 

the  face.  But  this  is  not  right,  and  it  is  really  of  importance  that 
the  slope  of  the  nose  should  be  observed  so  as  to  give  us  some  idea 
whether  the  usual  angle  of  crest  will  suffice  or  whether  some  change 
should  be  made.  Otherwise  the  sharp  cutting  edge  of  the  crest 
breaks  the  skin  of  the  nose  in  a  short  time,  making  an  ugly  sore 
that  it  is  impossible  to  heal  while  the  glasses  are  worn  with  the  angle 
of  crest  in  same  position.  The  patient  also  becomes  irritated  and 
is  apt  to  have  an  unpleasant  feeling  for  the  man  who  furnished  the 
glasses. 

'/ 

adi 


If  the  bearing  surface  of  the  bridge  of  the  nose  is  more  nearly 
vertical  than  normal,  the  lower  edge  of  the  crest  will  cut  into  the 
nose.  Or  if  the  slope  of  the  nose  is  more  nearly  horizontal,  the 
upper  edge  will  cut  into  the  flesh. 

A  neat  little  instrument  has  been  devised  for  measuring  the 
proper  angle  of  the  crest,  or  it  can  also  be  determined  by  a  card 
marked  with  radiating  lines  which  show  the  angle  of  the  slope  of 
nose  in  comparison  with  a  plane  lying  horizontally. 

The  angle  of  the  crest  then  you  will  understand  has  reference 
to  the  angle  formed  by  the  inside  surface  of  the  bridge  where  it 
rests  on  the  nose  with  a  horizontal  line.  300  would  be  a  small 
angle,   6o°  a  large  angle,   while  45 °  would  fit  the  average  nose. 

The  angle  of  the  lenses.  The  perpendicularity  of  the  plane  of 
the  lenses  to  the  visual  axis  is  an  important  matter,  the  rule  being 
that  the  lenses  shall  set  as  nearly  as  possible  at  right  angles  to  the 
visual  axes.  The  stronger  the  lens  the  more  the  importance  of  this 
rule  is  emphasized.  The  reason  for  this  lies  in  the  fact  that  the 
refractive  value  of  the  lens  is  changed  and  increased  when  placed 
obliquely  to  the  axis  of  vision. 

A  cylinder  when  misplaced  in  this  way  gives  the  effect  of  a 
stronger  cylindrical  lens  ;  a  sphere  not  only  an  increased  spherical 
effect  but  also  a  cylindrical  effect,  the  axis  being  at  right  angles  to 
the  meridian  about  which  the  lens  is  rotated. 

A  1  D.  cylindrical  lens  at  an  obliquity  of  300  gives  the  effect 
of  an  additional  half  diopter  ;  while  at  an  obliquity  of  400,  the 
cylindrical  effect  is  just  doubled. 


Spectacles  and  Eyeglasses 


235 


A  1  D.  sphere  at  an  obliquity  of  400  gives  an  increased 
sperical  effect  of  .  16  D.  with  the  addition  of  a  cylindrical  effect  of 
nearly  1  D. 


In  order  to  meet  the  requirements  of  perpendicularity  to  the 
visual  axis,  lenses  used  only  for  distance  should  be  vertical  as 
shown  in  diagram  on  blackboard. 


1 


In  near  vision  which  is  usually  below  the  level  of  the  eyes,  the 
visual  axes  are  directed  downwards  and  inwards,  and  here  the  lenses 
must  face  in  the  same  direction  in  order  to  maintain  the  desired 
perpendicularity,  as  shown  in  the  diagrams  on  the  blackboard. 


When  glasses  are  prescribed  for  constant  wear,  the  lenses  may 
be  placed  midway  between  the  adjustment  for  distance  and  for  near. 
In  this  case  the  inclination  is  not  exactly  correct  for  either  purpose, 
but  at  the  same  time  the  obliquity  to  the  visual  axis  in  either  case 
is  so  slight  as  to  cause  but  little  inconvenience,  because  it  is  only 
when  the  obliquity  is  marked  that  the  increase  in  power  and 
the  development  of  a  cylindrical  effect  in  spherical  lenses  is 
noticeable.  Of  course  a  moderate  degree  of  obliquity  of  the 
lenses  can  be  neutralized  by  a  slight  bending  of  the  neck  of 
the  wearer. 


236  Clinics  in  Optometry 

This  question  of  the  perpendicularity  of  lenses  is  a  most 
important  one  when  bifocal  glasses  are  prescribed,  and  these 
should  nearly  always  be  ordered  tilted  to  the  position  proper 
for  near  use.  It  has  frequently  been  my  experience  that  when 
patients  return  with  bifocals  complaining  that  they  were  not 
satisfactory,  a  re-examination  would  show  that  the  lenses  were 
correct,  and  on  further  investigation  it  would  be  found  that 
the  lenses  were  too  nearly  vertical  and  that  a  slight  tilt  as  for 
reading  was  all  that  was  necessary  to  make  them  comfortable  and 
satisfactory. 

When  the  temples  are  perpendicular  to  the  plane  of  the  glasses, 
the  latter  will  face  directly  forward  as  for  distant  vision.  When  it 
is  desired  to  make  them  face  downwards  as  for  reading,  the 
necessary  obliquity  may  be  obtained  by  simply  turning  down  the 
temples,  care  being  taken  that  they  are  equally  turned,  as  other- 
wise if  one  is  turned  more  than  the  other  the  lens  on  this  side  will 
be  higher  on  the  face  than  on  the  other. 

In  cases  also  where  the  lashes  are  long  and  where  it  is  difficult 
to  get  the  reading  glasses  close  enough  to  the  face,  the  patient  will 
probably  see  under  the  glasses  when  he  looks  down  for  reading. 
This  difficulty  can  be  overcome  by  bending  the  temple's  as  just 
described  so  as  to  make  the  lenses  tilt  inwards  at  the  bottom.  In 
most  cases  a  tilting  of  io°  will  suffice,  but  this  may  be  increased  to 
1 50  or  200  if  thought  necessary. 

The  width  of  temples.  The  temple  width  refers  not  to  the 
distance  from  joint  to  joint  across  the  frame,  but  to  the  distance 
between  points  on  the  temples  one  inch  back  from  the  front,  the 
reason  for  this  being  that  the  temples  come  in  contact  with  the 
sides  of  the  head  about  one  inch  back  from  the  plane  of  the  lenses, 
and  that  is  the  ' '  width  ' '  we  desire  to  measure. 

This  measurement  becomes  necessary  where  the  patient  has  a 
broad  face  with  perhaps  no  or  only  a  slight  increase  in  pupillary 
distance.  In  such  a  case  if  the  p.  d.  only  is  specified  in  the 
prescription,  on  account  of  the  disproportion  in  the  face,  tne  temple 
wires  will  cut  into  the  sides  of  the  head.  If  the  face  is  narrow  and 
the  temples  stand  out  from  the  head,  the  glasses  are  likely  to  be 
unsteady  when  walking  or  in  exercise,  and  especially  if  they  are 
heavy.  In  order  to  give  the  proper  support  to  the  lenses,  the 
temples  should  simply  touch  the  skin  without  any  pressure.  An 
occasional  patient  will   complain  if   there  is   the   slighest   contact 


Spectacles  and  Eyeglasses  237 

between  the  temple  and  skin,  when  it  may  become  necessary  to 
bend  the  temples  out  a  trifle  even  at  the  expense  of  losing  the 
support  which  the  glasses  would  otherwise  have. 


A  glance  at  the  diagram  I  have  made  on  the  blackboard  will 
perhaps  serve  to  make  my  meaning  still  clearer. 

The  length  of  temples.  When  this  measurement  is  mentioned, 
some  persons  think  it  refers  to  the  distance  from  the  temple  joint  to 
the  point  where  it  begins  to  curve  down  over  the  top  of  the  ear, 
which  varies  from  3^  to  4  inches.  But  I  think  it  would  save 
confusion  to  give  the  length  of  the  entire  temple. 

The  only  reason  why  the  length  should  be  given  from  joint  to 
top  of  ear,  is  that  the  manufacturer  may  put  a  sharp  curve  at  this 
point,  as  illustrated  on  blackboard. 


1 


But  unless  specified  in  the  prescription  the  manufacturer  will 
not  put  this  kink  in  the  temples  as  it  is  not  customary  to  do  so.  In 
spite  of  this  there  are  some  authorities  who  claim  that  the  proper 
form  for  hook  temples  is  a  straight  line  from  the  joint  to  top  of  ear, 
then  a  sharp  curve  and  finally  an  easy  curve  corresponding  to  back 
of  ear.  Therefore,  if  in  any  case  you  should  consider  it  desirable 
to  have  a  temple  of  this  shape,  you  had  better  do  the  bending 
yourself  after  the  frame  comes  from  the  hands  of  the  manufacturer. 
With  patience  and  a  little  experience,  the  temple  wire  can  be  bent 
to  follow  every  depression  and  elevation  of  the  surface  with  which 


238  Clinics  in  Optometry 

it  lies  in  contact  ;  this  is  especially  desirable  in  any  case  where  the 
auricle  is  deformed  or  irregular  in  shape. 

The  ordinary  length  of  the  entire  temple  is  six  inches  and  this 
will  be  found  to  answer  in  the  majority  of  cases.  If  you  do  not 
specify  any  particular  length  of  temple  in  your  prescription,  you 
will  receive  one  of  six  inches.  For  children  it  will  be  best  to  order 
one  5}4  inches  long,  or  in  small  young  children  one  of  5  inches. 
On  the  other  hand  if  the  face  is  full  and  the  head  large,  a  temple 
6%  or  7  inches  long  is  often  necessary. 

DEFECTS    EASILY    REMEDIED 

When  you  receive  the  glasses  and  fit  them  on  your  patient,  if 
the  temples  are  a  trifle  too  long,  and  you  do  not  wish  to  lose  the 
time  to  return  them  to  be  cut  off,  you  may  curl  the  tip  of  the 
temples  back  a  little  so  that  the  ball  on  the  end  will  not  press 
uncomfortably  into  the  flesh  behind  the  ear.  I  do  not  recommend 
this  procedure  except  where  the  excess  in  length  is  very  slight,  as 
otherwise  this  curl  on  the  end  of  temples  may  be  unsightly  and 
distasteful  to  the  patient. 

If  the  glasses  are  inclined  to  slip  down  the  nose,  the  curve  of 
the  temples  should  be  shortened  by  drawing  them  between  a  pen- 
holder (or  any  smooth  round  object)  and  the  finger,  pressure 
being  made  against  the  inner  side  of  the  curve.  While  if  the 
glasses  are  drawn  too  tightly  toward  the  eyes,  the  curve  may  be 
lengthened  by  drawing  the  temples  between  the  finger  and  pen- 
holder, the  pressure  in  this  case  being  made  against  the  outer  side 
of  the  curve. 

You  should  be  careful  to  see  that  both  temples  stand  at  the 
same  angle  as  illustrated  on  the  blackboard  ; 


Spectacles  and  Eyeglasses  239 

If  one  temple  forms  a  larger  angle,  the  lens  on  that  side  will  be 
drawn  closer  to  the  face,  so  that  the  lashes  or  even  the  lids  may 
touch  the  glass. 


If  the  ears  are  both  on  the  same  level,  each  temple  must  make 
the  same  angle  with  the  front,  otherwise  one  lens  may  be  too  high 
and  the  other  too  low,  or  if  one  ear  is  higher  than  the  other,  as  not 
infrequently  happens,  one  temple  must  be  raised  or  the  other 
lowered  to  overcome  the  difference.  If  the  temple  is  bent  down 
near  the  joint,  the  lens  on  this  side  will  be  made  to  stand  higher, 
while  if  the  temple  is  bent  up,  the  lens  on  this  side  will  be  lowered. 

If  you  find  the  glasses  do  not  set  straight,  you  can  raise  one 
lens  or  lower  the  other  as  may  seem  best  to  you,  by  bending  the 
temple  down  or  up  with  round-jawed  pliers  used  close  up  the  joint. 
If  both  temples  are  turned  downwards,  the  effect  is  not  to  raise  both 
lenses  but  to  tilt  them  forwards  as  for  reading,  as  I  have  previously 
told  you. 

All  I  have  said  about  length  of  temples  refers  of  course  to 
riding  bows  or  hook  temples  ;  when  straight  temples  are  desired 
(which  is  seldom  now-a-days)  the  length  is  not  specified  in  the 
prescription,  except  perhaps  to  indicate  whether  the  ordinary 
length  will  suffice  or  whether  they  should  be  extra  long. 


Inspection  of  Spectacles  and  Eyeglasses  and 
Neutralization  of  Lenses 


[Clinic  No.  36] 

It  is  a  matter  of  prudence  and  importance  that  you  should 
carefully  examine  the  finished  product  as  received  from  the  manu- 
facturer in  order  to  determine  if  your  prescription  has  been  faith- 
fully filled.  Neglect  of  this  precaution  may  nullify  the  results  of 
your  patient  and  skilful  work  in  measuring  the  error  of  refraction. 
Therefore  it  becomes  absolutely  necessary  for  you  to  know  how  to 
test  and  neutralize  lenses  correctly  and  expeditiously,  as  well  as  to 
correct  any  mal-adjustment  of  the  frame  or  mounting  that  becomes 
apparent  when  placed  on  the  patient's  face. 

INSPECTION   OF    SPECTACLES 

In  the  case  of  frames  examine  the  lenses  to  see  if  they  are  in 
properly.  You  know  that  a  lens  can  move  in  the  eye  wire  so  that 
one  end  or  the  other  will  tilt  up  or  down,  which  in  the  case  of 
cylinders  becomes  a  serious  matter.  Take  your  screwdriver  and 
loosen  the  screw,  turn  the  lens  to  its  proper  position,  and  then 
tighten  the  joint. 

Turn  the  glasses  sidewise  to  see  if  they  are  both  on  the  same 
plane  :  if  not,  there  is  probably  a  twist  in  the  bridge,  which  can  be 
rectified  by  the  use  of  two  pliers,  one  for  holding  and  the  other  for 
turning.  If  there  is  a  concave  surface  on  the  lens  (as  in  periscopic 
convex)  see  that  it  is  next  to  the  eye.  If  both  surfaces  are  con- 
cave, see  that  the  strongest  concave  is  next  to  the  eye. 

Place  the  glasses  on  patient's  face  to  see  if  the  angle  of  the 
lenses  is  right  ;  nearly  vertical  for  distance,  or  tilted  for  reading. 
See  that  the  temples  work  smoothly  in  the  joints  :  sometimes  the 
loosening  of  the  screw  or  the  application  of  a  drop  of  oil  becomes 
necessary.  Note  the  angle  of  the  crest  of  the  bridge  and  see  that 
it  corresponds  to  the  slope  of  the  nose.  See  that  the  width  of  the 
base  of  the  bridge  is  right  so  that  it  fits  the  nose  neatly.  If  it  is 
too  tight  or  too  loose,  the  half-round  pliers  can  be  used  to  widen 
or  narrow  it,  which  if  much  will  necessitate  bending  of  the  shanks 
of  the  bridge  in  order  to  keep  the  lenses  in  alignment. 


Inspection  of  Spectacles  a?id  Eyeglasses  241 

Note  if  the  pupillary  distance  is  as  ordered,  and  see  if  the 
temples  fit  comfortably  against  the  side  of  the  head  :  the  wires 
must  not  cut  into  the  flesh,  neither  must  they  stand  away  from  the 
skin.  Either  of  these  faults  can  be  remedied  by  bending  temples 
close  to  joints,  but  care  must  be  taken  to  see  that  both  temples  are 
at  the  same  angle,  else  the  glasses  will  not  be  equally  distant  from 
the  eye. 

If  the  ears  are  sensitive  and  if  in  spite  of  loosening  the  curve 
of  the  temple  as  much  as  allowable,  complaint  is  made  of  the 
pressure  on  the  cartilage  of  the  ear,  in  which  case  you  may  slip  a 
piece  of  fine  rubber  tubbing  over  the  wires  to  prevent  the  cutting, 
or  use  a  special  device  now  on  the  market  for  this  purpose. 

ADJUSTING    EYEGLASSES 

As  I  have  told  you  before  the  guards  of  eyeglasses  should  con- 
form to  the  slope  of  the  sides  of  the  nose,  with  a  little  extra  tight- 
ness at  the  tops  to  prevent  tilting  forwards.  Then  attention  should 
be  given  to  the  spring  to  see  if  it  is  too  tight  or  not  tight  enough, 
or  if  the  tension  is  just  about  right.  You  can  tighten  the  spring 
with  half-round  pliers  and  weaken  it  with  flat-nosed  pliers.  If  the 
guards  fit  properly,  it  is  not  necessary  that  the  spring  should  be 
tight  ;  in  fact,  we  want  to  avoid  all  unnecessary  pressure  as  other- 
wise your  patient  will  soon  have  a  sore  nose.  Another  point  is  to 
see  that  the  spring  is  of  the  proper  length,  and  this  is  something 
that  is  often  overlooked.  When  you  alter  the  tension  of  the  spring, 
you  will  find  it  necessary  also  to  readjust  the  guards. 

If  the  lenses  of  eyeglasses  droop,  they  can  be  raised  by  bend- 
ing the  spring  just  where  it  enters  the  stud  closer  to  the  lenses, 
and  at  the  same  time  bending  the  lower  parts  of  the  guards 
inwards.  If  the  lenses  tilt  up,  the  spring  should  be  bent  away  from 
the  lenses  and  the  lower  parts  of  the  guards  bent  outwards. 

If  one  of  the  lenses  sets  farther  from  the  eye  than  the  other, 
you  should  look  to  see  if  the  fault  does  not  lie  in  the  bearing  sur- 
faces of  the  guards,  when  probably  a  little  slant  made  in  the  faulty 
one  will  bring  the  lens  into  proper  position. 

DETERMINING   THE    STRENGTH    OF    LENSES 

In  the  inspection  of  a  lens  the  first  point  to  be  determined  is 
whether  it  is  convex  or  concave.  If  the  lens  is  strong  the  convex 
or  concave  curves  are  so  marked  that  as  soon  as  we  look  at  the 


242 


Clinics  in  Optometry 


lens  we  can  see  its  character.  But  in  the  weaker  lenses  that  are  in 
common  use,  we  are  accustomed  to  determine  this  point  by  the 
apparent  motion  caused  by  the  lens. 

I  take  the  lens  in  my  hand,  holding  it  eight  or  ten  inches  from 
my  eye  and  looking  through  it  at  the  letters  on  the  distant  test 
card.  I  then  move  the  lens  from  side  to  side,  and  this  will  cause 
an  apparent  motion  in  the  letters  looked  at.  If  the  motion  is  in 
the  same  direction  as  the  lens  is  moved,  it  is  concave  ;  if  the  motion 
is  opposite,  convex.  By  this  means  it  is  easy  to  detect  as  low  a 
power  as  .  12  D.  and  any  one  can  use  it  without  any  special  skill  or 
preparation. 

Instead  of  moving  the  lens  from  side  to  side,  it  may  be  moved 
closer  to  and  farther  from  the  eye.  If  the  object  looked  at  magni- 
fies as  the  lens  is  pushed  away  from  the  eye,  it  is  convex  ;  if  it  grows 
smaller,  concave.  There  is  one  precaution  that  should  be  observed 
in  both  of  these  methods,  and  that  is  in  the  case  of  convex  lenses, 
which  must  be  held  within  their  focal  distance,  or  the  results  will  be 
reversed. 

Having  determined  in  this  way  if  the  lens  is  convex  or  concave, 
the  next  step  is  to  ascertain  if  it  is  simple  or  compound,  and  whether 
cylinder  or  prism  is  present.  Holding  the  lens  in  your  hand  at  a 
distance  from  your  eye  as  before,  look  through  it  at  some  object 
presenting  a  straight  line,  as  the  window  sash  or  a  picture  frame. 


Inspection  of  Spectacles  and  Eyeglasses  243 

Rotate  the  lens  around  the  visual  line  acting  as  a  longitu- 
dinal axis,  and  note  the  effect  on  the  straight  line  which  you 
have  selected  for  observation. 

PROVING    PRESENCE    OF    A    CYLINDER 

If  that  portion  of  the  line  seen  through  the  lens  appears  to 
move,  or  in  other  words  if  there  is  a  break  in  the  continuity  of  the 
line  seen  through  the  lens  as  compared  with  that  above  and  below 
it,  then  a  cylinder  is  proven  to  be  present.  If  this  oblique  displace- 
ment is  in  a  direction  contrary  to  the  motion  of  the  lens,  the  cylin- 
der is  convex  :  if  in  the  same  direction  as  the  motion,  concave. 
The  drawing  on  the  blackboard  indicates  the  action  of  a  convex 
cylinder.  To  locate  the  position  of  the  axis  of  the  cylinder,  it 
should  be  slowly  rotated  until  the  line  seen  above,  below  and 
through  the  lens  is  continuous,  as  illustrated  on  the  blackboard. 
The  line  would  also  be  continuous  in  the  meridian  at  right  angles 
to  the  axis  ;  in  other  words,  the  line  is  continuous  only  in  the  chief 
meridians  of  the  lens,  viz.,  the  meridians  of  least  and  greatest 
refraction.  In  the  case  of  a  weak  cylinder  (.12  D.  or  .25  D. )  the 
oblique  motion  produced  is  slight  and  you  must  watch  closely  to 
detect  it.  In  a  cylinder  of  higher  power  (1  D.  and  over)  the  effect 
is  very  pronounced.  I  would  advise  you  all  to  get  a  few  cylindri- 
cal lenses  of  various  strengths  and  spend  some  little  time  in  prac- 
ticing with  them  until  you  become  proficient  in  the  detection  of  a 
cylinder. 

In  looking  through  a  lens  at  a  straight  line,  there  is  one  word 
of  caution  I  wish  to  give  you,  and  that  is  not  to  confound  lateral 
displacement  with  oblique  displacement.  In  looking  through  a 
simple  sphere  at  any  place  except  its  optical  center,  the  straight 
line  will  be  broken,  but  the  broken  lines  will  be  parallel,  and  they 
can  be  made  to  coincide  not  by  rotating  the  lens  but  by  moving  it 
from  side  to  side.  But  in  the  case  of  a  cylinder  the  displacement 
seen  through  the  lens  is  oblique  and  is  caused  not  by  moving  the 
lens  from  side  to  side,  but  by  rotating  it. 

TO    DETERMINE    SPHERICAL    LENSES 

The  majority  of  lenses  are  spheres,  either  simple  or  compound, 
that  is,  at  least  one  surface  is  spherical  in  curvature. 

Sometimes  we  meet  with  piano  cylinders,  in  which  lenses  there 
is  no  power  in  the  meridian  of  the  axis,  all  the  refractive  value  being 


244  Clinics  in  Optometry 

in  the  meridian  at  right  angles.  In  testing  to  determine  if  a  lens  is 
a  simple  sphere,  we  may  use  the  straight  line  again,  rotating  the 
lens  around  its  optical  center  and  taking  care  to  keep  the  latter  in 
alignment  with  the  straight  line  :  if  no  "twisting"  action  is  devel- 
oped, there  can  be  no  cylinder  present. 

DETECTING    PRESENCE    OF    A    PRISM 

To  determine  a  prism.  The  presence  of  a  prism  in  a  lens  is 
usually  disclosed  by  simple  inspection  and  noticing  a  difference  in 
thickness  in  the  two  opposite  edges  of  the  lens. 

In  the  absence  of  a  prism  the  edges  of  the  lens  should  be  of 
the  same  thickness  at  opposite  points.  Of  course,  if  the  prism  is  of 
low  degree,  it  may  escape  detection  on  a  casual  examination  ;  but 
we  have  a  very  simple  method  by  which  we  may  determine  its 
presence.  Hold  the  lens  in  the  fingers  as  previously  described  and 
look  at  the  same  straight  line  directly  through  the  optical  center. 
If  the  line  is  continuous  above,  below  and  through  the  center,  the 
absence  of  a  prism  is  proven.  But  if  the  line  is  broken,  a  prism  is 
present,  the  displacement  of  that  portion  of  the  line  seen  through 
the  lens  being  in  the  direction  of  the  apex. 

Proving  the  optical  center.  Before  handing  the  finished 
glasses  to  your  patient,  each  lens  should  be  carefully  examined  with 
reference  to  the  position  of  its  optical  center  and  also  the  distance 
between  the  two,  as  otherwise  an  error  in  these  important  particu- 
lars may  be  overlooked.  In  the  cheap  glasses  sold  by  peddlers 
and  in  the  five  and  ten-cent  stores,  proper  centering  is  probably 
the  exception,  such  glasses  being  known  as  second-class  or  even 
third-class. 

In  first-quality  lenses,  unless  otherwise  ordered,  we  assume 
that  the  lenses  are  properly  centered  and  that  the  optical  center 
and  the  geometrical  center  coincide,  as  otherwise  our  measure- 
ments for  pupillary  distance,  however  carefully  made,  are  vitiated, 
and  an  undesired  prismatic  effect  introduced  into  the  lenses. 
Therefore  it  becomes  necessary  for  you  to  be  able  to  locate  the 
optical  center  of  a  lens,  which  can  be  easily  done  as  follows  : 

Place  a  rectangular  card  on  the  table  or  tack  it  on  the  wall  ; 
hold  the  lens  some  distance  from  it  and  from  your  eye.  The  edges 
of  the  card  seen  through  and  outside  of  the  card,  will  appear  con- 
tinuous only  when  the  corner  of  the  card  is  exactly  at  the  optical 


Inspection  of  Spectacles  and  Eyegla 


245 


center  of  the  lens.     This  I  have  illustrated  in  the  diagram  on  the 
blackboard,  No. 


In  diagram  No.  2  the  lens  is  improperly  held  in  relation  to  the 
card,  while  in  No.  3  the  lens  being  correctly  held,  the  optical  center 
is  shown  to  be  displaced  downwards  and  sideways.  If  this  method 
is  used  with  care,  the  results  are  satisfactorily  accurate. 


246 


Climes  in  Optometry 


2Veutralizatio?i  of  spherical  lenses.  To  neutralize  is  to  nullify 
or  make  of  no  effect.  As  I  told  you  a  few  moments  ago  when  we 
look  through  a  convex  or  a  concave  lens  in  motion,  a  certain  effect 
is  produced  on  the  object  looked  at,  causing  it  to  move  against  or 
with.  When  we  neutralize  the  lens  we  destroy  or  stop  all  such 
effect  or  motion.     Neutralization  is  the  most  common  method  of 


measuring  the  strength  of  lenses.  In  taking  a  lens  in  your  hand 
for  this  purpose,  you  first  determine  whether  it  is  convex  or  con- 
cave by  the  method  I  have  already  described  to  you,  and  at  the 
same  time  you  gain  some  idea  of  the  strength  of  the  lens,  because 
the  more  rapid  the  movement  of  the  object  looked  at,  the  stronger 
the  lens. 

If  the  lens  in  your  hand  is  convex,  you  take  from  the  trial  case 
a  concave  of  the  estimated  strength,  and  place  them  in  apposition 
center  to  center,  and  make  a  trial  of  the  combination  as  you  pre- 
viously made  of  the  single  lens,  and  carefully  note  the  apparent 
movement. 

1.  If  the  motion  is  still  opposite,  then  the  concave  lens  you 
have  chosen  is  too  weak,  and  another  and  stronger  must  be  tried. 

2.  If  on  the  contrary  the  motion  is  now  in  the  same  direction 
as  the  two  lenses  are  moved,  then  your  concave  lens  is  too  strong 
and  a  weaker  one  must  be  tried. 


Inspection  of  Spectacles  and  Eyeglasses  247 

3.  If  no  motion  is  apparent  the  neutralization  is  perfect,  and 
you  are  looking  through  what  corresponds  to  a  piano  lens,  because 
the  power  of  the  convex  lens  has  been  destroyed  by  the  concave 
and  the  value  of  the  first  lens  can  be  read  off  the  handle  of  the  sec- 
ond lens,  always  taking  the  precaution  to  change  its  sign. 

Therefore,  to  determine  the  strength  of  a  spherical  lens,  you 
combine  it  with  successive  lenses  of  opposite  sign  from  the  trial  case 
until  one  is  found  that  checks  all  motion.  In  lenses  of  high  power 
we  watch  for  the  neutralization  at  or  near  the  center  of  the  lens,  as 
motion  and  distortion  may  still  be  noticeable  near  the  periphery. 

Neutralization  of  cylindrical  lenses.  You  have  already  deter- 
mined that  the  lens  is  cylindrical  according  to  the  method  previ- 
ously explained  to  you  and  also  its  nature,  whether  convex  or  con- 
cave. In  moving  the  lens  you  have  discovered  the  meridian  in 
which  there  is  no  motion,  which  indicates  the  position  of  the  axis, 
and  the  neutralizing  cylinder  taken  from  the  trial  case  must  be 
placed  with  its  axis  in  exactly  the  same  position.  If  the  lens  under 
test  is  a  convex  cylinder,  then  you  must  try  successive  concave 
cylinders  until  one  is  found  that  stops  motion  in  all  directions.  If 
a  concave  cylinder  1.50  D.  with  its  axis  vertical  is  required,  then 
the  lens  under  examination  is  +  1.50  D.  cyl.  axis  900. 

A  sphero-cylindrical  lens.  This  is  a  compound  lens  composed 
of  a  sphere  and  a  cylinder,  and  its  neutralization  is  a  matter  of 
some  difficulty,  especially  for  beginners.  With  such  a  lens  there  is 
motion  in  all  directions,  but  you  will  soon  find  that  there  is  one 
meridian  in  which  motion  is  least  rapid.  Take  from  the  trial  case 
a  sphere  of  the  proper  sign  and  strength  to  neutralize  the  move- 
ment in  this  meridian.  You  will  find  there  is  still  motion  in  the 
meridian  at  right  angles  ;  in  other  words,  by  the  use  of  the  sphere 
to  neutralize  one  meridian,  you  have  now  in  your  hand  what 
amounts  to  a  plane  cylinder,  which  you  proceed  to  neutralize 
according  to  the  method  I  have  just  described  to  you.  The  neu- 
tralizing lenses  you  have  now  in  your  hand  are  a  sphere  and  a 
cylinder,  which  represent  the  value  of  the  lens  you  are  testing. 
For  instance,  if  your  neutralizing  lenses  are  +  1.50  D.  sphere  and 
+  1  D.  cylinder  with  axis  held  horizontally,  then  the  compound 
lens  you  are  testing  is  —  1.50  D.  S.  Q  —  1  D.  cyl.  axis  1800.  In 
a  case  like  this  where  two  lenses  are  required  for  neutralization, 
you  will  at  first  find  some  difficulty  in  handling  all  three  of  the 
lenses  at  once  and  keeping  the  axis  in  the  proper  position. 


248  Clinics  in  Optometry 

Neutralizing  Prisms.  The  strength  of  a  prism  may  be 
expressed  in  two  ways  :  by  its  refracting  angle  or  by  its  power  to 
bend  a  ray  of  light  from  its  course.  The  latter  system  has  advan- 
tages over  the  former,  but  this  is  a  point  which  we  have  not  the 
time  to  discuss  at  present. 

A  prism  may  be  neutralized  by  another  prism  taken  from  the 
trial  case  and  placed  in  apposition,  the  base  of  one  over  the  apex  of 
the  other.  A  straight  line  viewed  through  the  prism  is  broken, 
that  part  seen  through  the  lens  being  deflected  towards  the  apex. 
The  neutralizing  prism  with  base  over  apex  would  bring  the  line 
back  and  if  of  the  proper  strength  make  it  continuous. 

Neutralization  affords  a  most  satisfactory  method  of  determining 
the  refractive  value  of  a  lens,  whether  simple  or  compound,  but  it 
has  its  disadvantages.  Sometimes  you  may  get  a  perfect  neutraliza- 
tion by  a  sphere  and  cylinder  both  of  which  are  concave,  thus  show- 
ing convex  values,  and  yet  by  the  feel  and  shape  of  the  lens  you 
know  that  one  of  its  surfaces  is  concave.  Let  me  illustrate  by 
writing  two  formulae  on  the  blackboard  ; 

+  1.50  D.  S.  O  -f  1  D.  cyl.  axis  900 
+  2.50  D.  S.  C  —  1  D.  cyl.  axis  1800 

By  following  the  method  I  have  described  to  you  of  neutral- 
izing the  weakest  meridian  first  and  then  the  other  meridian  by  a 
cylinder,  you  will  get 

—  1.50  D.  S.  O  —  1  D.  cyl.  axis  900 

and  you  assume  that  the  lens  is  the  one  first  written  (+  O  +), 
but  as  you  examine  the  surfaces  of  the  lens  you  can  see  that  the 
inside  surface  is  concave  cylindrical.  Now  the  fact  of  the  matter 
is  that  this  is  all  in  transposition.  The  two  lenses  whose  formulae 
are  written  on  the  blackboard  have  the  same  refractive  value,  one 
being  transposable  into  the  other,  and  by  means  of  neutralizing 
lenses  you  can  determine  only  the  refractive  value  of  the  combina- 
tion, but  not  the  curvature  of  each  surface. 

The  Lens  Measure.  This  leads  me  to  mention  the  lens 
measure,  a  little  instrument  which  I  would  advise  you  all  to 
purchase,  as  affording  the  quickest  and  most  convenient  method  of 
determining  the  strength  and  composition  of  lenses,  although  at 
the  same  time  I  would  insist  that  you  should  first  be  a  master  of  the 
art  of  neutralizing  lenses  from  the  trial  case. 


Inspection  of  Spectacles  and  Eyeglasses 


249 


You  are  all  familiar  with  the  appearance  of  a  lens  measure,  and 
you  probably  all  know  that  of  the  three  projecting  pins  the  two  out- 
side ones  are  stationary,  while  the  central  one  being  movable  shows 
the  amount  of  curvature  which  is  indicated  by  the  hand  on  the  dial. 

I  have  frequently  handed  a  lens  and  the  measure  to  a  young 
student  and  asked  him  to  tell  me  the  strength  of  the  lens.  He 
presses  it  against  one  surface,  the  hand  moves  around  to  2. 25  on 
the   convex   side,    and    he   answers   "plus  2.25."      "That  is  not 


correct,' *  I  say.  He  tries  it  again,  the  hand  stops  at  the  same 
place,  and  he  looks  at  me  in  bewilderment  when  I  shake  my  head 
no.  Now,  what  is  the  trouble,  or  wherein  does  the  error  of  the 
student  lie? 

Let  me  say  to  you  and  emphasize  it,  that  every  lens  has  two 
surfaces  and  both  of  them  must  be  taken  into  account.  The 
trouble  with  our  friend  was  that  he  measured  one  surface  only. 

Both  surfaces  of  the  lens  must  be  measured  separately  and  then 
their  values  combined  by  means  of  algebraic  addition  :  Sometimes 
both  surfaces  have  the  same  curvature,  as  in  bi-convex  or  bi-concave, 
sometimes  one  surface  is  convex  and  the  other  concave,  as  in 
periscopic,  and  sometimes  one  surface  spherical  and  the  other 
cylindrical  as  in  sphero-cylinders. 

Now,  then,  taking  the  lens  which  our  friend  tried  to  measure, 
on  pressing  the  measure  against  the  other  surface  we  find  it  to  be 


250  Clinics  in  Optometry 

—  1.25  D.,  which  as  you  know  is  the  standard  for  the  concave 
surface  of  periscopic  convex  lenses.  Now  then  by  algebraic 
addition,  we  have 

-f  2.25  D. 

—  1-25  P. 

+  1  D. 

This  lens  then  is  a  periscopic  lens  whose  value  is  -J-  1  D. 
The  lenses  in  the  trial  case  are  double,  that  is,  the  same  curva- 
ture on  both  sides.     I  will  take  one  and  measure  it,  finding  +1.25 
D.  on  both  sides. 

+  1.25  D. 
+  1-25  P. 
+  2.50  P. 

By  algebraic  addition  we  find  the  value  of  this  lens  is  +  2. 50  P. 

Keeping  the  measure  steadily  pressed  against  the  lens,  I 
rotate  it  through  all  the  meridians  of  the  lens  at  the  same  time 
watching  the  dial  :  if  the  pointer  remains  stationary,  the  curvature 
of  the  surface  is  spherical,  its  value  being  indicated  by  the  figures 
at  which  the  pointer  stops.      Both  surfaces  are  tried  in  the  same  way. 

If,  however,  a  rotation  of  the  measure  causes  the  hand  to  move, 
you  will  know  that  you  have  to  do  with  a  cylindrical  surface.  You 
turn  the  measure  to  the  point  where  the  hand  points  to  zero,  and 
the  three  points  are  then  standing  on  the  axis  of  the  cylinder. 
Turning  the  measure  again  you  see  the  power  begin  to  increase 
until  at  right  angles  to  the  axis,  the  full  strength  of  the  cylinder  is 
shown.  If  you  are  measuring  a  piano  cylinder,  the  opposite  surface 
will  be  plane  and  the  hand  will  point  to  zero  in  all  meridians.  If 
the  lens  is  a  sphero-cylinder,  you  must  measure  both  surface  to 
discover  its  refractive  value.  If  the,  lens  measure  shows  +  1  P. 
in  all  meridians  on  one  surface,  and  +  1  P.  in  the  horizontal 
meridian  and  zero  in  the  vertical  meridian  on  the  other  surface,  the 
lens  is  +  1  P.  S.  C  +  1  P-  cyl.  axis  900. 


INDEX 


Abduction,  26,  107 
Accommodation,  spasm  of,  191 
Adduction,  26,  107 
Adjusting  of  glasses,  230 

of  spectacles,  215 
Albuminuric  retinitis,  177 

acuteness  of  vision  in,  177 
characteristic  features  of,  181 
impairment  of  vision  in,  177 
in  pregnancy,  179 
optic  disk  in,  177 
significance  of,  179 
use  of  ophthalmometer  in,  177 
use  of  pin-hole  disk  in,  177 
Amblyopia,  66  , 

acuteness  of  vision  in,  67 
hysterical,  29 
preventable,  66 
use  of  prisms  in,  67 
use  of  trial  case  in,  67 
Amblyopia,  toxic,  35  . 

ophthalmoscopic  examination  in,  36 
Aniridia,  145 
Anisometropia,  case  of,  78 

acuteness  of  vision  in,  84 
causes  of,  81 

considerations  in  correcting,  83 
examination  of  patient,  78 
impaired  vision  in,  78 
ophthalmometric  examination  in,  79 
ophthalmoscopic  examination  in,  79 
optic  disk  in,  79 
use  of  Maddox  rod  in,  80 
use  of  test  lenses  in,  79 
varieties  of,  82 
Astigmatism  against  the  rule,  134 

compound  hypermetropic,  135 
compound  myopic,  136 
cornea  in,  136 
definition,  135 
mixed,  136 

ophthalmometric  examination  in,  138 
simple  hypermetropic,  135 
simple  myopic,  136 
test-case  examination  in,  138 
Astigmatism,   case  of,    illustrating  value  of 

ophthalmometer,  115 
Astigmatism,  trial-case  test  in,  119 

compound    hypermetropic   with     pres- 
byopia, 46 
Astigmatism,  hypermetropic,  simulating  my- 
opic, 20  . 
acuteness  of  vision  in,  20 
fogging  test  in,  22 
Maddox  rod  in,  21 
muscular  equlibrium  in,  21 
testing  for,  20 
use  of  prisms  in,  22 
Astigmatism,  lenticular,  141 
abnormal,  142 
cases  of?  144 
cornea  in,  142 
exceptional  cases  of,  148 
seat  of,  142 
Astigmatism,  mixed,  71 
cause  of,  207 
cycloplegic  in ,  75 
definition  of,  73 


Astigmatism,  mixed 

examination  of  patient,  72 

fogging  test  in,  74 

stenopaic  slit  in,  76 

subjective  tests  of,  75 

test  letters  in,  75 
Astigmatism  of  the  lens,  dynamic,  145 
Astigmatism,  simple  hypermetropic,  9 

Maddox-rod  test  in,  12 

trial-case  test  in,  10 

with  normal  vision,  9 

with  the  rule,  11 
Astigmatism,  symmetric,  with  the  rule,  118 
Astigmatism,  routine  of  examination  in,  121 
Astigmatism  with  the  rule,  128 

compound  hypermetropic,  130 

compound  myopic,  131 

cornea  in,  129 

correction  of,  131 

direct,  129 

examination  of  patient  in,  131 

explanation  of,  129 

hypermetropic,  129 

indirect,  129 

mixed,  with  the  rule,  131 

mvopic,  129 

simple  hypermetropic,  130 

simple  myopic,  130 

use  of  ophthalmometer  in,  129 
Asthenopia,  23 

exophoric,  204 
Atropine,  26 


Bifocals,  236 

Blind  spot,  174 

Bridge,  the,  220,  233 
height  of,  220 
inclination  of,  220 
measurement  of  220 
width  of  base  of,  221 

Bright's  disease,  the  eye  in, 


Cataract,  41 

definition  of,  41 

incipient,  42 

pupil  in,  41 

refractive  error  diagnosed  as,  41 

revealed  by  ophthalmoscope,  41 
Choked  disk,  180 
Choroidal  atrophy,  148 
Choroidal  ring,  174 
Ciliary  muscle,  11,  33,  193 

contraction  of,  124 

in  myopia,  61 

in  spasm  of  accommodation,  193 

relaxation  of,  124 
Circles  of  diffusion,  35 
Color  vision  in  toxic  amblyopia,  38 
Concave  lenses,  116,  152 

decentration  of,  152 

use  of,  116 
Conical  cornea,  155 

cause  of,  161 

iridectomy  in,  163 

myotic  in,  163 


252 


Clinics  in  Optometry 


Conical  cornea 

testing  for,  155 

use  of  ophthalmometer  in,  156 
use  of  pin-hole  test  in,  156 
use  of  trial  lenses  in,  156 

Conjunctiva,  hyperaemia  of,  194 

Conjunctivitis,  196 

Contact  glasses,  162 

Conus,  the,  150 

Convergence,  deficiency  of,  200 

Convex  lenses,  115 

effects  of  strong,  124 

use  of  in  examination,  115 

Corneal  curvature,  normal,  30 

Crescent,  angle  of,  233 

Cross  cylinder,  73 

Crystalline  lens,  removal  of,  15S 

Cylinder,  proving  presence  of,  243 

Cycloplegia,  simulated,  74 

Cycloplegic,  use  of,  123 


Dark  room,  172 
Deeentration,  152 

rule  for,  153 
Diplopia,  artificial,  80 

artificial  vertical,  202 

crossed,  203 

homonymous,  12,  22,  185 

heteronymous,  80 
Divergence,  power  of,  15 
Duetion  test,  17 


Esophoria,  12, 17,  127,  184 

accommodation  in,  184 

acuteness  of  vision  in,  184 

cases  of,  184 

headache  in,  185 

measurement  of,  185 

method  of  testing  for,  184 

of  low  degree,  16 

prisms  in,  189 

symptoms  of,  188 

treatment  of,  188 
Exophoria,  107,  127,  199 

acuteness  of  vision  in,  199 

case  of,  199 

causes  of,  201 

diagnosis  of,  202 

effect  of  lenses  on,  27 

muscular  insufficiency  in,  200 

prismatic  lens  in,  204 

prism  exercise  in,  205 

symptoms  of,  200 

treatment  of,  204 

use  of  Maddox  rod  in,  200 

use  of  ophthalmometer  in,  199 

use  of  retinoscope,  199 
Eye,  cataphoric,  123 

hypermetropic,  32 

hyperphoria  113 

mental  picture  of  the,  137 

myopic,  61 
Eyeglass  fitting,  223 
Kyeglass,  inspection  of,  240 

measurement  of,  228 

mountings,  228 
Eyeglasses,  simple  fitting,  229 
Eves,  different  sizes  of,  225 


Facultative  hypermetropia,  103, 122 

Kitting  eyeglasses,  223 

Pitting  frames,  221  . 

Fogging  method  in  hypermetropia,  al 

in  myopia,  126 


Fovea  centralis,  174 
Fusion  faculty,  the, 


Guards,  227 

different  styles  of,  227 


H 

Headache  and  eyestrain,  30,  97 

asthenopic,  99 

causes  of,  98 

glasses  as  a  cure  for,  98 

in  connection  with  myopia  and  exo- 
phoria,  97 
Heterophoria,  detection  of,  21 

latent,  16 

mixed,  14 
Hypermetropia,  103 

absolute,  105 

acuteness  of  vision  in,  103 

detecting  presence  of,  103 

facultative,  105 

fogging  method  in,  106 

illustrating  fogging  method,  122 

latent,  105,  123 

Moddox  rod  in,  127 

manifest,  105 

measuring  amount  of,  103 

muscular  equilibrum  in,  32 

muscle  testing  in,  106 

objective  examination  in,  J 04 

prescribing  glasses  for,  107,  127 

simulating  myopia,  63 

symptoms  of.  103 

testing  for,  104 

typical  cases  of,  30 

use  of  ophthalmometer  in,  122 

use  of  retinoscope  in,  33 
Hypermetrope,  sight  of  the,  31 
Hyperphoria,  109 

acuteness  of  vision  in,  109 

aetiology  of,  112 

examination  for,  109 

fogging  system  in,  110 

headaches  in,  111 

latent,  112 

Maddox  rod  in,  111 

manifest,  17 

muscular  equilibrium  in.  111 

prescribing  prisms  for,  113 

retinoscope  test  in,  110 

treatment  of,  113 
Hysteria,  25,  191 
Hvsteria  and  eyestrain,  27 
Hysteria,  eye  manifestations  of,  29 

K 

Keratoconus,  155 
cause  of,  161 
iridectomy  in,  163 
myotic  in,  16:; 
testing  for,  155 

use  of  ophthalmometer  in.  156 
use  of  pin-hole  test  in,  156 
use  of  trial  case  in,  156 


Lachrymatinn,  194 

Lenticular  astigmatism,  141 

Dens,  sphero-cylindrical,  78,  24, 

Lenses,  angle  of,  2:i4 

cylindrical,  neutralization  of,  247 
determining  kind  of,  242 
determining  strength  of,  241 
inspection  of,  241 


Index 


253 


Lenses 

neutralization  of,  240 

prismatic,  19 

size  of,  225 

spherical,  neutralization  of,  246 

toric,  159 

transposition  of,  203 
Leucouia,  41 

M 

Macula  lutea,  174 

Maddox-rod  test  in  presbyopia,  57 

in  anisometropia,  80 

in  astigmatism,  12,  21 

in  esophoria,  200 

in  hypermetropia,  32 

in  hyperphoria,  109 
Maddox  multiple  rod,  16 
Meniscus,  162 
Monocular  vision,  66 

acuteness  of  vision  in,  55 

fogging  test  in,  68 

impaired  vision  in,  66 

pin-hole  test  in,  65 

retina  in,  66 

retinsocopic  test  in,  68 

tenotomy  in,  66 
Mydriatics,  use  of,  172 
Mvopia,  58 

definition  of,  62 

false,  63 

in  children,  64 

optic  disk  in,  59 

pin-hole  test  in,  60 

prescribing  glasses  for,  61 

subjective  test  for,  59 

use  of  ophthalmoscope  in,  59 

use  of  retinoscope  in,  59 

use  of  trial  case  in,  59 

visual  acuity  in,  58 
Myopia,  accommodative,  197 

apparent,  197 

artificial,  124 

simulative,  194 
Myopia,  high,  148 

accommodation  in,  149 

cause  of,  148 

extraction  of  lens  in,  154 

heredity  as  cause  of,  150 

investigating  cause  of,  150 
Myopic  crescent,  148,  150 


N 

Near  point,  the,  20 
Neutralization  of  lenses,  246 

cylindrical,  247 

prisms,  248 

spherical,  24R 
Night  blindness,  175 
Nystagmus,  175 


Ocular  gymnastics,  206 
Ophthalmometer,  15,  30,  117 
how  to  use,  117 
importance  of,  120 
in  albuminuric  retinitis,  177 
in  anisometropia,  78 
in  astigmatism,  115,  129,  207 
in  esophoria,  199 
in  hypermetropia,  122 
in  keratoconus,  156 
in  pigmentary  retinitis,  170 
in  strabismus,  89,  92 
Ophthalmoscope,  170 
evolution  of,  170 
in  cataract,  42 


Ophthalmoscope 

in  myopia,  59 

in  pigmentary  retinitis,  170 

in  presbyopia,  57 

in  toxic  amblyopia,  35 

invention  of,  171 

limitations  of,  44 

Loring's,  172 

use  of,  170 
Optical  centering,  244 
Optical  disk,  173 

color  of,  173 

examination  of,  173 

shape  of,  174 
Optic  nerve,  244 


Papillitis,  180 
Perimeter,  37 

in  strabismus,  95 

presence  of,  39 

use  of,  95 
Photophobia,  194 
Physiologic  cup,  174 
Pigmentary  retinitis,  170 

use  of  ophthalmometer  in,  170 

use  of  ophthalmoscope  in,  171 

use  of  optic  disk  in,  174 
Pin-hole  test,  35 

in  albuminuric  retinitis,  177 

in  keratoconus,  156 

in  strabismus,  92 

in  toxic  amblyopia,  36 
Pliers,  230 

use  of  in  adjusting,  230 

use  of  in  gold  filled  goods,  230 
Presbyopia,  52 

acuteness  of  vision  in,  53 

amplitude  of  accommodation  in,  56 

glasses  to  prescribe  in,  54 

illustrated  case  of,  53 

muscular  equilibrium  in,  57 

testing  for,  53 

use  of  ophthalmoscope  in,  57 

use  of  retinoscope  in,  57 
Primary  position,  117 
Prism  exercises,  27 

effect  of,  28 
Prisms,  18,  22,  244. 

detecting  presence  of,  244 

neutralization  of,  248 
Pupillary  distance,  218 

measurement  of,  219 


Radiating  lines,  11,  75 

Recti  muscles,  112 

Retina  of  a  squinting  eye,  86 

Retinal  hemorrhage,  179 

Retinoscope,  25,  33 

handling  mirror  of,  167 
in  exophoria,  199 
in  hypermetropia,  33 
in  hyperphoria,  110 
in  myopia,  59 
in  presbyopia,  57 
in  strabismus,  89,  165 
use  of,  165 

Retinoscopy,  163 

principles  of,  163 
value  of,  163 


Scleral  ring,  174 
Scotoma,  38 
Secondary  position,  118 


254 


Clinics  in  Optometry 


Spasm  of  accommodation.  191 
ciliary  muscle  in,  195,  197 
diagnosis  of,  191,  195 
lachrymation  in,  194 
photophobia  in,  194 
symptoms  of,  194 
treatment  of,  196 
Spectacle  measurements,  how  to  make,  232 
Spectacles,  adjustment  of,  215 
frames  of,  217 
frameless,  218 
inspection  of,  240 
measurements  for,  217 
mountings,  217 
rimless,  218 
skeleton,  218 
styles  of,  218 
Spectacles  and  eyeglasses,  231 
Spring,  the  Grecian,  229 
Springs  for  eyeglasses,  226 
Staphyloma,  posterior,  148,  150 
Stenopaic  slit,  76 

Strabismus,  convergent,  68,  85,  164 
aetiology  of,  87 
binocular  vision  in,  85 
cure  of,  87 
definition  of,  85 
deviation  in,  164 
Donder's  investigation  of,  87 
examination  of  patient,  89 
fusion  faculty  in,  88 
objective  testing  of, 
use  of  ophthalmometer  in  89 
use  of  prisms  in,  90 
use  of  retinoscope  in,  89 
■with  hypermetropia,  93,  164 
Strabismus,  divergent,  91 

acuteness  of  vision  in,  91 


Strabismus,  divergent 

measuring  the  degree  of,  95 

method  of  examination,  91 

treatment  of,  93 

use  of  ophthalmometer  in,  92 

use  of  pin-hole  disk  in,  VI 

with  myopia,  93 
Strabismus,  convergent,  caused  by  hyperme- 
tropia, 163 

objective  method  of  examination,  164 

retinoscopic  test  in,  165 

prescribing  glasses  for,  169 
Strabismus,  high  convergent,  111 

latent,  186 

manifest,  186 
Studs,  outset,  228 

different  sizes  of,  226 


Temples,  236 

length  of,  237 

width  of,  236 
Transposition  of  lenses,  207 
Trial  frame,  three-cell,  158 


Urea  in  nephritis,  181 

V 

Vertical  streak,  22 

Vitreous  humor,  opacity  of,  148 

Y 

I    Yellow  spot,  188 


PHYSIOLOGIC  OPTICS 

Ocular  Dioptrics — Functions    of    the  Retina — Ocular 
Movements  and  Binocular  Vision 


By  Dr.  M.  Tscherning 

Director  of  the  Laboratory  of  Ophthalmology  at  the   Sorbonne,   Paris. 


AUTHORIZED    TRANSLATION 
By  Carl  Weiland,  M.  D. 

Former  Chief  of  Clinic  in  the  Eye  Department  of  the  Jefferson  College  Hospital, 
Philadelphia,   Pa. 


This  book  is  recognized  in  the  scientific  and  medical 
world  as  the  one  complete  and  authoritative  treatise  on 
physiologic  optics.  Its  distinguished  author  is  admittedly 
the  greatest  authority  on  this  subject,  and  his  book  embodies 
not  only  his  own  researches,  but  those  of  the  several  hundred 
investigators  who,  in  the  past  hundred  years,  made  the  eye 
their  specialty  and  life  study. 

Tscherning  has  sifted  the  gold  of  all  optical  research  from 
the  dross,  and  his  book,  as  now  published  in  English,  with 
many  additions,  is  the  most  valuable  mine  of  reliable  optical 
knowledge  within  reach  of  ophthalmologists.  It  contains  380 
pages  and  212  illustrations,  and  its  reference  list  comprises  the 
entire  galaxy  of  scientists  who  have  made  the  century  famous 
in  the  world  of  optics. 

The  chapters  on  Ophthalmometry,  Ophthalmoscopy,  Ac- 
commodation, Astigmatism,  Aberration  and  Entoptic  Phenom- 
ena, etc. — in  fact,  the  entire  book  contains  so  much  that  is  new, 
practical  and  necessary  that  no  refractionist  can. afford  to  be 
without  it. 

Bound  in  Cloth.     380  Pages,  212  Illustrations. 
Price  $2.50  (10s.  5d.) 


Published   by 

The   Keystone   Publishing  Co. 
809-81 1-813  North  19TH  Street,  Philadelphia,  U.  S.  A. 


TESTS  AND  STUDIES 

OF  THE 

OCULAR  MUSCLES 


By  Ernest  E.  Maddox,  M.  D.,  F.  R.  C.  S.,  Ed. 

Ophthalmic  Surgeon  to  the   Royal  Victoria  Hospital,   Bournemouth,   England;   formerly 
Syme    Surgical    Fellow,    Edinburgh    University. 


Tests  and  Studies 

of  the 

Ocular  Muscles 


This  book  is  universally  recog- 
nized as  the  standard  treatise  on 
the  muscles  of  the  eye,  their  func- 
tions, anomalies,  insufficiencies, 
tests  and  optical  treatment. 

All  opticians  recognize  that  the 
subdivision  of  refractive  work  that 
is    most    troublesome    is    muscular 
anomalies.     Even  those  who  have 
mastered  all  the  other  intricacies  ot 
visual  correction  will  often  find  their 
skill    frustrated    and    their    efforts 
nullified  if  they  have  not  thoroughly 
mastered  the  ocular  muscles. 
The  eye  specialist  can  thoroughly  equip  himself  in  this 
fundamental  essential  by  studying  the  work  of  Dr.  Maddox 
who  is  known  in  the  world  of  medicine  as  the  greatest  in- 
vestigator and  authority  on  the  subject  of  eye  muscles. 

The  present  volume  is  the  second  edition  of  the  work, 
specially  revised  and  enlarged  by  the  author.  It  is  copiously 
illustrated  and  the  comprehensive  index  greatly  facilitates 
reference. 

Bound  in  silk  cloth— 261   pages— no  illustrations. 
Sent  postpaid  on  receipt  of  price  $1.50  (6s.  3d.) 


Published  by 

The  Keystone   Publishing  Co. 
809-81 1-813  North  19TH  Street,  Philadelphia,  U.  S.  A. 


THE 

PRINCIPLES  of  REFRACTION 

in  the  Human  Eye,  Based  on  the  Laws  of 
Conjugate  Foci 


By  Swan  M.  Burnett,  M.  D.,  Ph.  D. 

Formerly   Professor   of   Ophthalmology  and   Otology   in   the   Georgetown   University 
Medical  School;  Director  of  the  Eye  and  Ear  Clinic,  Central  Dispensary 
and  Emergency  Hospital;  Ophthalmologist  to  the  Children's  Hos- 
pital and  to  Providence  Hospital,  etc.,  Washington,  D.  C. 


In  this  treatise  the  student  is  given  a  condensed  but  thor- 
ough grounding  in  the  principles  of  refraction  according  to  a 
method  which  is  both  easy  and  fundamental.  The  few  laws 
governing  the  conjugate  foci  lie  at  the  basis  of  whatever  per- 
tains to  the  relations  of  the  object  and  its  image. 

To  bring  all  the  phenomena  manifest  in  the  refraction  of 
the  human  eye  consecutively  under  a  common  explanation  by 
these  simple  laws  is,  we  believe,  here  undertaken  for  the  first 
time.  The  comprehension  of  much  which  has  hitherto  seemed 
difficult  to  the  average  student  has  thus  been  rendered  much 
easier.  This  is  especially  true  of  the  theory  of  Skiascopy, 
which  is  here  elucidated  in  a  manner  much  more  simple  and 
direct  than  by  any  method  hitherto  offered. 

The  authorship  is  sufficient  assurance  of  the  thoroughness 
of  the  work.  Dr.  Burnett  was  recognized  as  one  of  the  great- 
est authorities  on  eye  refraction,  and  this  treatise  may  be 
described  as  the  crystallization  of  his  life-work  in  this  field. 

The  text  is  elucidated  by  24  original  diagrams,  which 
were  executed  by  Chas.  F.  Prentice,  M.E.,  whose  pre-emi- 
nence in  mathematical  optics  is  recognized  by  all  ophthalmol- 
ogists. 

Bound  in  Silk  Cloth. 

Sent  postpaid  to  any  part  of  the  world  on  receipt  of  price, 

$1.00  (4s.  2d.) 


Published  by 

The  Keystone  Publishing  Co. 
809-81 1-813  North  19TH  Street,  Philadelphia,  U.  S.  A. 


THE   OPTICIAN'S    MANUAL 

VOL.  I. 


By  C.  H.  Brown,  M.  D. 


Graduate    University    of    Pennsylvania;    Professor    of    Optics    and    Refraction;    formerly 
Physician   in   Philadelphia   Hospital;    Member   of   Philadelphia   County, 

Pennsylvania    State    and    American     Medical    Societies. 


The  Optician's  Manual,  Vol.  I,  was 
the  most  popular  and  useful  work  on 
practical  refraction  ever  written,  and  has 
been  the  entire  optical  education  of 
many  hundred  successful  refractionists. 
The  knowledge  it  contains  was  more  ef- 
fective in  building  up  the  optical  profes- 
sion than  any  other  educational  factor. 
It  is,  in  fact,  the  foundation  structure  of 
all  optical  knowledge  as  the  titles  of  its 
ten  chapters  show : 

—Introductory  Remarks. 

— The  Eye  Anatomically. 

—The  Eye  Optically;  or,  The  Physiology  of  Vision. 

. — Optics. 

— Lenses. 

— Numbering  of  Lenses. 

— The  Use  and  Value  of  Glasses. 

—Outfit  Required. 

— Method  of  Examination. 

— Presbyopia. 

The  Optician's  Manual,  Vol.  T,  was  the  first  important 
treatise  published  on  eye  refraction  and  spectacle  fitting.  It 
is  the  recognized  standard  text-book  on  practical  refraction, 
being  used  as  such  in  all  schools  of  Optics.  A  study  of  it  is 
essential  to  an  intelligent  appreciation  of  its  companion  treatise. 
The  Optician's  Manual,  Vol.  II,  described  on  the  opposite 
page.  A  comprehensive  index  adds  much  to  its  usefulness  to 
both  student  and  practitioner. 

Bound  in  Cloth — 422  pages— colored  plates  and  illustrations. 
Sent  postpaid  on  receipt  of  $1.50  (6s.  3d.) 


Chapter 

I.- 

Chapter 

II. 

Chapter 

III. 

Chapter 

IV, 

Chapter 

V.- 

Chapter 

VI. 

Chapter 

VII. 

Chapter 

VIII. 

Chapter 

IX.- 

Chapter 

X. 

Published  by 

The  Keystone  Publishing  Co. 
809-81 1 -8 13  North  19TH  Street,  Philadelphia,  U.  S.  A. 


THE  OPTICIAN'S  MANUAL 

VOL.   II. 


By  C.  H.  Brown,  M.  D. 

Graduate    University    of   Pennsylvania;    Professor   of   Optics    and    Refraction;    formerly 

Physician   in   Philadelphia    Hospital;    Member   of   Philadelphia   County, 

Pennsylvania   State   and    American   Medical    Societies. 


The  Optician's  Manual,  Vol.  II.,  is 
a  direct  continuation  of  The  Optician's 
Manual,  Vol.  I.,  being  a  much  more 
advanced  and  comprehensive  treatise. 
It  covers  in  minutest  detail  the  four 
great  subdivisions  of  practical  eye  re- 
fraction, viz: 

Myopia. 
Hypermetropia. 
Astigmatism. 
Muscular  Anomalies. 

It  contains  the  most  authoritative  and  complete  re- 
searches! up  to  date  on  these  subjects,  treated  by  the  master 
hand  of  an  eminent  oculist  and  optical  teacher.  It  is  thor- 
oughly practical,  explicit  in  statement  and  accurate  as  to  fact. 
All  refractive  errors  and  complications  are  clearly  explained, 
and  the  methods  of  correction  thoroughly  elucidated. 

This  book  fills  the  last  great  want  in  higher  refractive 
optics,  and  the  knowledge  contained  in  it  marks  the  standard 
of  professionalism. 

Bound  in  Cloth— -408  pages — with  illustrations. 
Sent  postpaid  on  receipt  of  $1.50  (6s.  3d.) 


Published  by 

The   Keystone  Publishing  Co. 

809-811-813  North  19TH  Street,  Philadelphia,  U.  S.  A. 


OPHTHALMIC  LENSES 

Dioptric  Formulas  for  Combined  Cylindrical  Lenses, 

The  Prism-Dioptry  and  Other  Original  Papers 


By  Charles  F.  Prentice,  M.E. 

A  new  and  revised  edition  of  all  the  original  papers  of  this  noted 
author,  combined  in  one  volume.  In  this  revised  form,  with  the  ad- 
dition of  recent  research,  these  standard  papers  are  of  increased  value. 
Combined  in  one  volume,  they  are  the  greatest  compilation  on  the 
subject  of  lenses  extant. 

This  book  of  over  200  pages  contains  the  following  papers: 

Ophthalmic   Lenses. 

Dioptric  Forimilse  for  Combined  Cylindrical   Lenses. 

The   Prism-Dioptry. 

A  Metric  System  of  Nnijobering;  and  Measuring  Prisms. 
The  Relation  of  the  Prism-Dioptry  to  the  Meter  Angle. 
The  Relation  of  the  Prism-Dioptry  to  the  Lens-Dioptry. 

The   Perfected  Prisiiioineter. 

The  Prismometrie   Scale. 

On    the    Practical    Execution    of   Ophthalmic   Prescriptions    In- 
volving Prisms. 

A  Problem  in  Cemented  Bl-Focal  Lenses,  Solved  by  the  Prism- 
Dioptry. 

Why    Strong   Contra-Generic   Lenses  of   Equal   Power  Fail    to 
Neutralize  Each  Other. 

The  Advantages    of    the    Sphero-Toric    Letts. 

The   Iris,  as   Diaphragm   and   Photostat. 

The  Typoscope. 

The  Correction  of  Depleteil  Dynamic  Refraction   (Presbyopia). 

PRESS  NOTICES  ON  THE  ORIGINAL  EDITION: 
Ophthalmic    Lenses. 


"The  work  stands  alone,  in  its  present 
form,  a  compendium  of  the  various  laws 
of  physics  relative  to  this  subject  that  are 
so  difficult  of  access  in  scattered  treat* 
ises."—  New  England  Medical  Gazette, 

"It  is  the  most  complete  and  beat  il- 
lustrated book  on  this  special  subject  ever 
published."—  Horoloi/ieal  Review,  New 
York. 


"Of  all  the  simple  treatises  on  the 
properties  of  lenses  that  we  have  seen, 
this  is  incomparably  the  best.  .  .  . 
The  teacher  of  the  average  medical  stu- 
dent will  hail  this  little  work  as  a  great 
btnm."  -Avehivis  of  Ophthalmology,  cd- 
ited   by  If.   Kiuipp,  M.D. 


Dioptric    Formula?    for   Combiued    Cylindrical    Lenses. 


"This  little  brochure  solves  the  prob- 
lem oi  combined  cylinders  in  all  its  as- 
pects, and  in  a  manner  simple  enough  (or 
the  comprehension  of  the  average  student 
of  ophthalmology.  The  author  is  to  be 
congratulated  upon  the  success  that  has 
erowned  his  labors,  for  nowhere  is  there 
to  he  found  so  simple  and  yet  so  complete 
an    explanation    as    is    contained    in    those 

pages."— A  reft  ires  of  Ophthalmology,  ed- 
ited by  B.  Knapp,  M.n. 


"This  exhaustive  work  of  Mr.  Trentice 
is  a  solution  of  one  of  the  most  difficult 
problems  in  ophthalmological  optics. 
Thanks  are  due  to  Mr.  Prentice  for  the 
excellent  manner  in  which  he  lias  eluci- 
dated a  subject  which  has  not  hitherto 
been  satisfactorily  explained." — The  Oph- 
thalmic   Review,    London. 


The  book  contains  1 10  Original  Diagrams.     Bound  in  cloth. 
Price  $1.50  (6s.  3d.) 


Published  by 

The  Keystone  Publishing  Co. 

809-81  i-Si 3  North  iqth  Street,  Philadelphia,  U.  S.  A. 


SKIASCOPY 

AND  THE  USE  OF  THE  RETINOSCOPE 


By  Geo.  A.  Rogers 

srly   Professor   in    the   Northern   Illinois   College   of   Ophthalmology   and   Otology, 
Chicago;    Principal    of    the    Chicago    Fost-Graduate    College    of 
Optometry;    Lecturer    and    Specialist    on 
Scientific   Eye    Refraction. 


A  Treatise  on  the  Shadow  Test 
in  its  Practical  Application  to  the 
Work  of  Refraction,  with  an  Ex- 
planation in  Detail  of  the  Optical 
Principles  on  which  the  Science 
is  Based. 


This  work  far  excels  all  previous  treatises  on  the  sub- 
ject in  comprehensiveness  and  practical  value  to  the  refrac- 
tionist.  It  not  only  explains  the  test,  but  expounds  fully  and 
explicitly  the  principles  underlying  it — not  only  the  phe- 
nomena revealed  by  the  test,  but  the  why  and  wherefore  of 
such  phenomena. 

It  contains  a  full  description  of  skiascopic  apparatus,  in- 
cluding the  latest  and  most  approved  instruments. 

In  depth  of  research,  wealth  of  illustration  and  scientific 
completeness  this  work  is  unique. 

Bound  in  cloth;  contains  231  pages  and  73  illustrations 
and  colored  plates. 

Sent  postpaid  to  any  part  of    the    world    on    receipt    of 

$1.00  (4s.  2d.) 


Published  by 
The  Keystone  Publishing  Co. 
809-81 1-813  North  19-ra  Street,  Philadelphia,  U.  S.  A. 


Optometric  Record  Book 


A  record-book,  wherein  to  record  optometric  examina- 
tions, is  an  indispensable  adjunct  of  an  optician's  outfit. 

The  Keystone  Optometric  Record-book  was  specially  pre- 
pared for  this  purpose.  It  excels  all  others  in  being  not  only  a 
record-book,  but  an  invaluable  guide  in  examination. 

The  book  contains  two  hundred  record  forms  with  printed 
headings,  suggesting,  in  the  proper  order,  the  course  of  ex- 
amination that  should  be  pursued  to  obtain  most  accurate  re- 
sults. 

Each  book  has  an  index,  which  enables  the  optician  to 
refer  instantly  to  the  case  of  any  particular  patient. 

The  Keystone  Record-book  diminishes  the  time  and 
labor  required  for  examinations,  obviates  possible  oversights 
from  carelessness,  and  assures  a  systematic  and  thorough  ex- 
amination of  the  eye,  as  well  as  furnishes  a  permanent  record 
of  all  examinations. 

Sent  postpaid  on  receipt  of  $1.00  (4s.  2d.) 


Published  by 

Thr   Keystone  Publishing  Co. 
809-81 1-813  North  19TH  Street,  Philadelphia,  U.  S.  A. 


14  DAY  USE 

RETURN  TO  DESK  FROM  WHICH  BORROWED 

OPTOMETRY  LIBRARY 

This  book  is  due  on  the  last  date  stamped  below,  or 

on  the  date  to  which  renewed. 

Renewed  books  are  subject  to  immediate  recall. 


LD  21-50,,,  6/59 
(A2845sl0)476 


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University  of  California 

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